Another Look at Prime Numbers

After 2, every prime must be ‘odd’; not dividible by two.
any number N times 2 mod 2 = 0
0+1=1
Thus 2n± 1 mod 2 =1, and 1 is not = to 0.
(n is a whole number)

After 2 and 3, every prime must neither be divisible by two or three.
Numbers not divisible by 2 can be represented by 2n± 1.
Numbers not divisible by 3 can be represented by 3n± 1 or 2.

These sets intersect at 6n± 1(or 5), which includes EVERY number not divisible by 2 or 3,
thus everyprime after 2 and 3 is a solution to 6n± 1 or 5.

This explains Vivek Zaveri 's method.

It was originally deduced by analyzing the position of prime in base 12,
where every prime after 2 and 3 is to the left or right of the column of 6’s multiples, which aren’t multiples of 12, similar to the column of 5’s odd multiples in base 10.

0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19

Hi:

I love your site. The absolute best way to teach math is the way you do it.

I didn’t have time to go through all the comments, but I noticed that you didn’t explicitely mention the fundamental theorem of arithmetic, or the unique prime factorization theorem: Every integer greater than one is either a prime or is the product of a unique set of primes.

If I missed it somewhere, my apologies.

hi Sir Kalid :slight_smile:
Can you please help me? i have this mathematical investigation in our college and i have to make a modeling material that shows my investigation bout primes and their real life uses. Do you have any ideas how i can do that? thank you ! I’m deadmeat here.

Unless I missed something, I think you missed out a couple of multiplication signs in the Sum of Digits example; specifically the paragraph that starts “Let’s think about numbers with the “33” functional group.”

Also another typo: ““Not fitting in” is a great if it means”.

All of my posts of February 2011 should be DELETED because they contain a fundamental fallacy.
The fallacy is this: IN THE ALGEBRA OF NUMBERS, addition is distributive over multiplication. This is untrue.
In fact and this is easily proved that addition is NOT distributive over multiplication. However in the algebra of numbers, multiplication is distributive over addition.

The essential idea is that every uneven integer can be represented as a vector having a minimum number of components, depending on the said uneven integer, but any finite number of components greater than the minimum. The prime two plays a key role in the representation of any prime number that is an uneven integer. All the prime numbers with the exception of prime two are uneven integers, thus: [3, 5, 7, 11, … 7927, … to infinity ]
For example, 19 as a vector is: [16, 8, - 4, - 2, 1] and that is the minimal representation. Prime 19 is: [32, - 16, 8, - 4, - 2, 1] and
[64, - 32, - 16, 8, - 4, - 2, 1] et c. Representing prime numbers as vectors gives a different way of studying prime numbers and uneven composites using linear algebra to find linearly independent sets of vectors to form a basis spanning a given finite dimensional space.
The vectors representing; 3, 5, 7, 11 an 13 are dependent giving the linear combination: [x[1], … x[5]] = x[4].[ - 1, 1, 0, 1, -1], where x[4] can have any value. Noting that each of these vectors has five components.
However, the vectors representing 3, 5, 7, 11 and 17 are linearly independent, each vector having again five components. These linearly independent vectors span 5D space.

Finding sets of vectors representing primes that form linearly dependent sets looks like a most expeditions way to study primes.
Constructing square and rectangular matrices and solving the matrix equation AX = O, the zero vector using Gaussian elimination, looks like the best way in this context. Matrices having five rows seems to be do-able using pencil and paper.

But there is another way and that is to find sets of vectors that represent primes which span the entire space of a given dimension. The case of the primes 3, 5 and 7 spanning 3D space has been proved by solving the three equations cited below.

The case of 5D space is interesting because matrices with five rows are just do-able using pencil are paper. If such matrices have five columns, square matrices, then the five column vectors could span 5D space and thus be a basis set of linearly independent vectors. This means that if other vectors having five components are adjoined to make a rectangular matrix having five rows, then the new adjoined vectors would be some linear combination of the basis set of vectors. This implies a system of linear equations to be solved to find the linear combination.

A typical vector, here minimally representing prime 23 is: [16, 8, - 4, 2, 1]. A larger vector representing prime 23 is [32, - 16, 8, - 4, 2, 1].

It is advantageous to reclassify the primes thus:
[2] and [3, 5, 7, 11, 13, 17, … ], putting prime two into a class of its own. An integer in this context just means an uneven integer in the class:
[1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, … ], noting that the latter class of primes are a subclass of the integers in the above class. Composites are then integers in the class of uneven integers above. Typical composites are 9, 15, 21, 25, 27, 33, 35, … etc. The uneven integer unity, one [1] can be written as a vector having at least one component, itself, since N defined below is zero in this case, and there are [N + 1] components in a vector as a minimum. The integer one [1] can be written as an expression having at least one term, but any finite number of terms, thus:
1 = 2^{M} - 2^{M - 1} - … - 1. For example 1 = 16 - 8 - 4 - 2 - 1 giving as is seen below a 5D vector: [16, - 8, - 4, - 2, - 1].

The key fact is that when dividing an uneven integer by prime two, and having an uneven quotient in every instance, the remainders have to be either + 1 or - 1. The remainders cannot be anything else.

Formally if Q[N], an uneven integer, satisfies the inequality:
2^{N} < Q[N] < 2^{N + 1}, where N is 1, 2, 3 … then:

Q[N] = 2.Q[N - 1] + r[N - 1] and remainder r[N - 1] having the subscript [N - 1] is given by r[N - 1] = i^{1 + Q[N]} . The " i " is the imaginary number that satisfies the equation i^{2} + 1 = 0.
Counting down, Q[1] = 3 always, Q[0] = 1 and r[0] = 1. The remainder r[N] is conveniently defined as r[N] = 1, rather than r[N] = - 1, thereby fixing
Q[N + 1].

Starting from Q[1] = 2.Q[0] + r[0] and " condensing " the equations by successive elimination of Q[j]'s by multiplications by two until only Q[N] is left, an equation giving Q[N] in terms of the remainders r[1], … r[N - 1] and powers of two is arrived at. This is the minimal equation containing [N + 1] terms.
We have: Q[N] = 2^{N} + 2^{N - 1} + r[1].2^{N - 2} + … + r[N - 1].2^{0} and
2^{0} = 1, just to help the accounting.
Since 2^{N} = 2^{N + 1} - 2^{N} = 2^{N + 2} - 2^{N + 1} - 2^{N} etc. the term 2^{N} can be substituted by terms involving larger powers of prime two.
Vectors come in when the terms of the equation giving Q[N] are set in order and written as the components of a vector thus:
Q[N] as a vector is: [2^{N}, 2^{N - 1}, r[1].2^{N - 2}, … r[N - 1].2^{0}], having the minimum of [N + 1] components.

The essential matter to notice is that a vector representation of an uneven integer apart from the dimension, from a minimum dimension upwards, is unique to that uneven integer. The other matter to notice is that irrespective of dimension, subject to the minimum dimension, the algebraic sum of the components of the vector representing that uneven integer invariably reproduce that uneven integer.

A slight digression on linear independence.

The vectors that in 3D represent the primes; 3, 5 and 7 are respectively;
[4, - 2, 1], [4, 2, - 1] and [4, 2, 1]. How can it be shown that these three vectors are not dependent on one another, in other words, linearly independent ?

Ans. [a] draw a perspective picture [b] construct a model in three dimensions, a 3D model. In this case, the vertices of the vectors are the vertices of a spherical triangle of unequal sides. [c] solve the equations:
4 x[1] + 4 x[2] + 4 x[3] = 0, - 2 x[1] + 2 x[2] + 2 x[3] = 0 and
x[1] - x[2] + x[3] = 0 . The solutions are x[1] = 0, x[2] = 0 and x[3] = 0 The vectors are linearly independent.

In solving these equations, it is better to multiply the first equation by 1/4, the second equation by 1/2 and leave the third equation unaltered. This gives a new set of equations that have the same solutions as the original equations.
The proper and by far the best way to solve the simplified equations is using Gaussian elimination.

I just solve these equations in the simplest way by reverse substitutions.

In every case of solving equations involving uneven integers as vectors, it is best to remove by multiplication the descending powers of the prime two, but leave the last equation in 2^{0} terms unaltered.

Gaussian reduction works for square and rectangular systems of linear equations. In the case of rectangular systems it is usual that the number of columns, vectors representing uneven integers, exceeds the number of rows, number of components which is the dimension of the vectors.

A good way of picturing the succession of primes and composites, herein meaning uneven integers that are not primes, is to make a tableau. Using centimetre squared paper, accurately ruled, taking a sheet measuring more than 64 cm by more than 48 cm, to allow for a border, starting from x = 0 and y = 0, plotting the uneven integer along the x axis made parallel to the longer side, and plotting the components of the vector representing that particular uneven integer on the y axis that is parallel to the shorter side of the paper, then the primes from 3 to 61 can be accommodated as vectors of six dimensions. Putting N = 5 gives a six dimension vector [6D]. Four colours could be used for the primes. The greatest term 2^[5} could be one colour. The terms that are negative that exist for the smaller primes than 32 could be another colour. The positive term 2^{5 - 1}, which is 2^{4} could be another colour. The terms involving the remainders: r[1], … r[N - 1], here r[1],
r[2], r[3], and r[4], which are r[1].2^{3}, r[2].2^{2}, r[3].2^{1} and r[4].2^{0} could be the same, but another colour. If the composites are to be included, then the ordinates, the y co-ordinates could be marked using the same colour for all the composites, but different from all the other colours, of which there are at least three and at the most four colours. The tableau would then be a mosaic of dots of different colours.
There would be no point in joining any of the dots by straight lines, since this is likely to be meaningless.
Remembering that a composite here, such as 21, 45, 57 etc. is an uneven integer. Unity, one can be put on the tableau amongst the composites.

None of the above works if we put three in place of prime two, as
Q[N] = 3^{N} + etc. The result is nonsense. ONLY prime two gives the correct results.

There is a theorem discovered by Euclid of Alexandria who lived in Hellenistic Egypt around 300 BC, on the infinitude of the primes; [2, 3, 5, 7, 11, … to infinity] to which he gave a very simple proof. That is, Euclid proved very succinctly that there are infinitely many prime numbers. Euclid of Alexandria wrote the eponymously titled " Euclid’s Elements " and an algorithm named after him for which he is perhaps best known.

The usual definition of what constitutes a prime number is any number greater than zero that has no prime factors other than itself and one, unity.

There is another definition consistent with the definition above. This is: A prime number is an uneven integer that has an irrational square root, that when divided by every prime up to the greatest prime that is less than the square root of the said uneven integer gives a non-zero remainder. Since prime two is even, prime two could not divide an uneven integer.

The even integer two has an irrational square root but there exists no primes greater than unity but less than this square root. Therefore even integer two is a special case having no divisors except itself and unity, then two prime.

Likewise, uneven integer three has no prime divisors less than the irrational square root of three, since no prime divisors exist between one and the square root of three, three is prime.

This other definition of a prime number constitutes a proof that for:
1 < Q < 3^{2}, the uneven integers, Q in this range are each prime, because no prime numbers in the latter class: [3, 5, 7, 11, … ] exist that could be divisors of Q. That is; 3, 5 and 7 are prime. Since Q is uneven and two is even, that discounts prime two to divide Q with remainder zero.

Similarly, there are no integers between unity and the irrational square root of two that could divide the integer two, so that two has to be prime. Maybe sounds pedantic, but I was looking at the consequences of defining an uneven integer to be prime where all the lower prime divisors up to the greatest divisor that is less than the irrational square root of the said uneven integer produce a non-zero remainder.

The above definition citing a non-zero remainder only applies to primes greater than nine.

This looks OK for another definition of a prime number.

The latest news is a prime of 22000000 digits has been discovered. But we do not even know why the prime 23 occurs where it does, violating the symmetry of the prime distribution between 16 and 32.
Treating primes as vectors and doing the analysis requires a knowledge of linear algebra which right now I do not have.

I have found that the 5D [vectors having five components] representations of
3, 5 and 7 are linearly independent [L I]. The 5D vector representations of 3, 5, 7 and 11 are L I, but the vector representations of 3, 5, 7, 11 and 13 are dependent, such that [x[1], … x[5]] = x[4].[ -1, 1, 0, 1, -1], this being the dependent relationship.
The vectors representing 3, 5, 7, 11 and 17 are linearly independent. This means that the vectors representing: 13, 19, 23, 29 and 31 can be taken as the vectors [b] in A.X = b and solved for X = [x[1], … x[5]]. Since five component vectors representing 3, 5, 7, 11, 17 are L I, the vectors span 5D space.
There are ten primes sandwiched between 2^{1} and 2^{5}, and C[10, 5] selections, which is 10!/[5! 5!]. That is 252 selections of vectors, some of which could be linearly independent. The linearly independent selections might form a group.
In each L I selection, as in example: [3, 5, 7, 11, 17], there are five sets of solutions [x[1], … x[5]] for each of the other primes, of which there are five, as noted above. These solutions can be plotted to find if any regularity exists.
The set of solutions might constitute a group.

In the case of primes from 3 to 61 inclusive, six component vectors spanning 6D space could be found. In this case there are C[17, 6] selections which works out at 12376 selections. Solving all of the selections of 6D vectors taken six at a time to find the selections that are linearly independent, spanning 6D space, by hand is out of the question.
At least one linearly independent set of six vectors could be found and used to solve for the six vector components for each of the other remaining sixteen prime numbers.

The Alexandria has been added to distinguish him from Euclid of Megara.

Mentioning the use of prime numbers in cryptography, I saw no point in referring to a very advanced area of abstract algebra well beyond my scope and the scope of most but not all high school students. However, even the most advanced math can be made simple without being simplistic. An example of this is the Chinese Remainder Theorem in an online discussion that even I can follow. The word " simplistic " means skipping over the essential steps in a subject so as to make the subject appear better to understand but in reality not presenting any useful information what so ever.
An excessive simplification, a simplistic presentation, makes a subject like maths mystifying and unintelligible.
The maths I have written about expressing primes as vectors is or should be perfectly easy to understand, as it is not dauntingly difficult.

Prime numbers in the infinite class: [3, 5, 7, 11, … ] can be represented uniquely as vectors of any finite number of components, subject to a minimum number of components: [N + 1], where the said prime satisfies the inequalities:
2^{N} < Q < 2^{N + 1}. If you realize that division of an uneven integer, a prime in particular, by prime two to give an uneven integer quotient produces the remainders of either + 1 or - 1, then this is key to finding the expression, equation for a prime number, and the minimum vector to represent that prime. The remainders cannot be the familiar 0 and 1 in this form of division.
Thus: Q[N] = 2.Q[N - 1] + r[N - 1], where N and N - 1 are really subscripts, counting down.
The equation for a prime [uneven] or for an uneven integer is:
Q[N] = 2^{N} + 2^{N - 1} + r[1].2^{N - 2} + r[2].2^{N - 3} … r[N - 1].2^{0}
and 2^{0} = 1.
Since 2^{N} = 2^{N + 1} - 2^{N} = 2^{N + 2} - 2^{N + 1} - 2^{N} et c. for example: 8 = 16 - 8 = 32 - 16 - 8 etc., we can substitute for 2^{N} in the equation for Q[N] and indefinitely increase the number of terms.
The r[1], r[2], … r[N - 1] are the remainders of repeated division by two, counting down to r[1] . The remainder r[0] = 1 and the final iteration is:
Q[1] = 2.Q[0] + r[0]. Always, Q[1] = 3, Q[0] = 1 and r[0] = 1. Although r[N] does not appear here, r[N] is conveniently defined as r[N] = 1, thereby fixing one of the two possible values of Q[N + 1]. If r[N] = - 1, then the other value of Q[N + 1] is produced.
By taking the terms in order in the equation for Q[N], which lies between
2^{N} and 2^{N + 1}, the terms can be taken as the components of an [N + 1] dimensional vector. By increasing the number of terms as above, the number of components can be increased to any finite number of components.
For example prime 19 as a vector is: [16, 8, - 4, - 2 , 1] in five dimensions, the minimum for Q[4] = 19. Here N = 4, hence five dimensions.
Prime 19 in six dimensional space is: [32, - 16, 8, - 4, - 2, 1] et c.
Generally, an uneven integer Q[N] as a vector is:
[2^{N}, 2^{N - 1}, r[1].2^{N - 2}, r[2].2^{N - 3}, … r[N - 1].2^{0}] having [N + 1] components, the minimum number for Q[N].
Examples: prime 3 is [4, - 2, 1], 5 is [4, 2, - 1] and 7 is [4, 2, 1]. The vectors representing 3, 5 and 7 in 3D space are found to be linearly independent. Prime 3 minimally is [2, 1], as a vector.
By expressing, for example the primes from 3 to 61 inclusive, of which there are seventeen primes, as vectors having each in this case six components and plotting the components of each prime against the said prime, a picture can be seen of what the sequence of the primes looks like.
I think the mysteries of prime numbers will be solved using elementary linear algebra to find linearly dependent and linearly independent sets of vectors, each uniquely representing a prime number. Note that the algebraic sum of the components of a vector representing a prime number reproduces that prime number, only.
There is definitely an advantage in placing prime two and the other larger primes into two distinct classes, thus: [2] and [3, 5, 7, 11, 13, … ].
I hope that sooner, the puzzle of the apparently erratic prime sequence will be solved, but I think representing primes as vectors is central to the explanation.
I forgot to say how the remainders + 1 or - 1 are found when Q[N] is divided by prime two to invariably produce an uneven quotient, not necessarily a prime. For example: 53 = 2.27 + [ - 1] and 55 = 2.27 + [ + 1].
The simple general answer is: r[N - 1] = i^{1 + q[N]}. The number " i " satisfies i^{2} + 1 = 0. In this equation, " i " is the imaginary number.
If : the exponent of i: {1 + Q[N]} is divisible by two, but not by four, then
r[N - 1] = - 1. If {1 + Q[N]} is divisible by four, then r[N - 1] = + 1. Let’s see if this is true for the uneven integers 53 and 55. Here N = 5, since 53 and 55 lie between 32, 2^{5} and 64, 2^{6}.
The exponent {1 + 53} which is {54} is divisible by two, but not by four. The exponent {1 + 55} is divisible by four. So r[5 - 1] = - 1 in the case of Q[5] = 53 and r[5 - 1] = + 1 in the case of Q[5] = 55. The remainder r[5 -1], baby arithmetic, is r[4].
The remainders in the vectors appear implicitly as positive and negative algebraic signs.
The above maths is very simple and logical. The more difficult part comes with solving systems of linear matrix equations, whose columns are prime numbers expressed to the same number of components, five in the case below.
I have found that the primes; 3, 5, 7, 11 and 17 expressed as 5D vectors are linearly independent, but the primes: 3, 5, 7, 11 and 13 are dependent, but I intend to check my work. Given that: [3, 5, 7, 11, 17] [writing shorthand] are linearly independent, then these five vectors span five dimensional space. this means that the primes: 13, 19, 23, 29 and 31 are contained in the 5D space and we can solve for [x[1], … x[5]] for each of the primes; 13, 19 etc. and find out what is going on. My guess is that the solutions might be cyclic in the components, but it is only by doing the work, that the answers are found.
A typical column vector in the above five by five matrix would be 29 represented as: [16, 8, 4, 2, - 1] and 13 would be; [16, - 8, 4, 2, - 1]. In solving such a system of equations, the rows above the last row containing ones with the appropriate algebraic sign, can be multiplied by the non-zero constants 1/16, 1/8, 1/4 and 1/2. This is quite general, removing the powers of prime two. The matrix of coefficients then becomes a pattern of - 1’s and + 1’s only.
I hope you find the above interesting reading and Kalid finds this interesting as well.