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Linear primes p' = mp + n
Problem statement List the prime numbers of the form p' = mp + n for a given (m,n) couple and such that p' < k, k positive in...

1 year ago

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List the complementary / symetric prime couples
Problem statement For a given positive integer n, provide the prime couples (p,p') such that p + p' = 10^n. NB : a number li...

1 year ago

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Check Legendre's conjecture
Context and problem statement Legendre's conjecture states for a given positive integer n, there always exists at least one pri...

1 year ago

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Check Bertrand-Chebyshev's theorem about prime numbers
Historical context Bertrand's postulate, also later known as Chebyshev's theorem, is a very important theorem in number theory ...

1 year ago

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Check p = 6n +/- 1, the generic formula for odd prime numbers greater than 3
Problem statement For all odd prime number p greater than 3, there exists a positive integer n, such that p = 6n +/- 1 : ...

1 year ago

Solved

Check p = 4n +/- 1, the generic formula for odd prime numbers
Problem statement For all odd prime number p, there exists a positive integer n, such that p = 4n +/- 1 : Check this f...

1 year ago

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Monkey and the Peaches
A monkey picked a certain number of peaches on the first day. Each day, the monkey eats half of the remaining peaches plus one ...

1 year ago

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List the segmented numbers
The sequence of segmented numbers begins 1, 2, 4, 5, 8, 10, 14, 15, 16. Notice that none of the terms is the sum of consecutive ...

1 year ago

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List primes which are the sum of two consecutive lower primes plus minus one
Problem statement Some prime numbers can be written as the sum of two consecutive lower primes plus / minus one : Like t...

1 year ago

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Frequencies of prime gaps
Problem statement Given two positive integers n and , write a function which computes the frequency of the gap between two ...

1 year ago

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Prime numbers which are the difference of two consecutive cubes
Problem statement Given a positive integer n greater than 2, find the prime numbers less or equal to n and which are the diff...

1 year ago

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Find the first occurence of a given gap between two consecutive prime numbers
Problem statement Given a gap = p' - p between the two consecutive prime numbers p and p', find its first occurence, f. E...

1 year ago

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List the near-square primes, p = n² + 1 (Landau's 4th problem)
Historical context At the 1912 International Congress of Mathematicians, Edmund Landau listed four basic problems about prime...

1 year ago

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Implement a ROT13 cipher
Replace each character in string s1 with the character that is shifted 13 positions from it (wrap back to the beginning if neces...

1 year ago

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Mandelbrot Numbers
The <http://en.wikipedia.org/wiki/Mandelbrot_set Mandelbrot Set> is built around a simple iterative equation. z(1) = c z...

1 year ago

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Determine whether a number is a seesaw number
Cody Problem 60957 dealt with balanced primes. In that case, balance was measured in terms of the average of primes around a giv...

1 year ago

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Decimation
When dealing to the Roman Army, the term decimate meant that the entire unit would be broken up into groups of ten soldiers, and...

1 year ago

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Tic Tac Toe FTW
Given a tic tac toe board: * 1 represents X * 0 represents empty. * -1 represents O It is X's move. If there is an imme...

1 year ago

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Connect Four Win Checker
<http://en.wikipedia.org/wiki/Connect_Four Connect Four> is a game where you try to get four pieces in a row. For this problem, ...

1 year ago

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Given two arrays, find the maximum overlap
Given two (integer) arrays s1 and s2, create a new array s3 which is as short as possible and contains both arrays. #1 s1 = [...

1 year ago

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Pi Digit Probability
Assume that the next digit of pi constant is determined by the historical digit distribution. What is the probability of next di...

1 year ago

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It dseon't mettar waht oedrr the lrettes in a wrod are.
An internet meme from 2003 (read more here) asserted that readers are relatively insensitive to letter order in words, so long a...

1 year ago

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"mirror" matrix
Create n x 2n "mirror" matrix of this type: Examples For n = 2 m = [ 1 2 2 1 1 2 2 1 ] For n = 3 m = ...

1 year ago

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Kaprekar Steps
6174 is the Kaprekar constant. All natural numbers less than 10,000 (except some with same digits) can be reduced to 6174 in the...

1 year ago

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What is the next step in Conway's Life?
Given a matrix A that represents the state of Conway's game of Life at one instant (time t=n), return the matrix B that represen...

1 year ago

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Fibonacci sequence
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: Input...

1 year ago

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Convert from Fahrenheit to Celsius
Given an input vector F containing temperature values in Fahrenheit, return an output vector C that contains the values in Celsi...

1 year ago

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Swap the first and last columns
Flip the outermost columns of matrix A, so that the first column becomes the last and the last column becomes the first. All oth...

1 year ago

Solved

Create times-tables
At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 times 12 is way more th...

1 year ago

Solved

Column Removal
Remove the nth column from input matrix A and return the resulting matrix in output B. So if A = [1 2 3; 4 5 6]; ...

1 year ago