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Prime factor digits
Consider the following number system. Calculate the prime factorization for each number n, then represent the prime factors in a...

6 days ago

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Project Euler: Problem 18, Maximum path sum I
By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bott...

6 days ago

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Project Euler: Problem 16, Sums of Digits of Powers of Two
2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26. What is the sum of the digits of the number 2^N? Thanks ...

7 days ago

Solved

Proper Factors
Generate the proper factors of input integer x and return them in ascending order. For more information on proper factors, refer...

8 days ago

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Return fibonacci sequence do not use loop and condition
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: ...

9 days ago

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Divisors for big integer
Inspired by Problem 1025 and Project Euler 12. Given n, return the number y of integers that divide N. For example, with ...

9 days ago

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Project Euler: Problem 4, Palindromic numbers
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 ...

10 days ago

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Multiples of a Number in a Given Range
Given an integer factor _f_ and a range defined by _xlow_ and _xhigh_ inclusive, return a vector of the multiples of _f_ that fa...

10 days ago

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Factorize THIS, buddy
List the prime factors for the input number, in decreasing order. List each factor only once, even if the factorization includes...

10 days ago

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Get all prime factors
List the prime factors for the input number, in decreasing order. List each factor. If the prime factor occurs twice, list it as...

10 days ago

Solved

Sophie Germain prime
In number theory, a prime number p is a *Sophie Germain prime* if 2p + 1 is also prime. For example, 23 is a Sophie Germain prim...

11 days ago

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Find nearest prime number less than input number
Find nearest prime number less than input number. For example: if the input number is 125, then the nearest prime number whi...

11 days ago

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Largest Twin Primes
<http://en.wikipedia.org/wiki/Twin_prime Twin primes> are primes p1, p2 = p1 + 2 such that both p1 and p2 are prime numbers. Giv...

11 days ago

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Make a vector of prime numbers
Input(n) - length of vector with prime numbers Output(v) - vector of prime numbers Example: * n=1; v=2 * n=3; v=[2 3 5...

11 days ago

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Binary code (array)
Write a function which calculates the binary code of a number 'n' and gives the result as an array(vector). Example: Inpu...

11 days ago

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Right Triangle Side Lengths (Inspired by Project Euler Problem 39)
If p is the perimeter of a right angle triangle with integral length sides, { a, b, c }, there are exactly three solutions for p...

11 days ago

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Sum of big primes without primes
Inspired by Project Euler n°10 (I am quite obviously a fan). With problem n°250 by Doug, you can find some global methods to co...

11 days ago

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Sums of cubes and squares of sums
Given the positive integers 1:n, can you: 1. Compute twice the sum of the cubes of those numbers. 2. Subtract the square...

11 days ago

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Project Euler: Problem 10, Sum of Primes
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below the input, N. Thank you <http:/...

14 days ago

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Project Euler: Problem 9, Pythagorean numbers
A Pythagorean triplet is a set of three natural numbers, a b c, for which, a^2 + b^2 = c^2 For example, 3^2 + 4^2 = 9 + 16 ...

14 days ago

Solved

Project Euler: Problem 6, Natural numbers, squares and sums.
The sum of the squares of the first ten natural numbers is, 1^2 + 2^2 + ... + 10^2 = 385 The square of the sum of the first ...

14 days ago

Solved

Create logical matrix with a specific row and column sums
Given two numbers *|n|* and *|s|*, build an |n-by-n| logical matrix (of only zeros and ones), such that both the row sums and th...

22 days ago

Solved

Specific Element Count
Given a vector _v_ and a element _e_, return the number of occurrences of _e_ in _v_. Note: NaNs are equal and there may be n...

22 days ago

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middleAsColumn: Return all but first and last element as a column vector
Given input A, return all but the first and last elements, arranged as a column vector. (I.e., all dimensions after the first s...

22 days ago

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Matrix indexing with two vectors of indices
Given a matrix M and two index vectors a and b, return a row vector x where x(i) = M(a(i),b(i)).

22 days ago

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Getting logical indexes
This is a basic MATLAB operation. It is for instructional purposes. --- Logical indexing works like this. thresh = 4...

22 days ago

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Reindex a vector
You are given two vectors of equal length. Vector N has numeric values (no Inf or NaN) while vector IDX has integers. Place th...

22 days ago

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Get the elements of diagonal and antidiagonal for any m-by-n matrix
In the problem <http://www.mathworks.com/matlabcentral/cody/problems/858-permute-diagonal-and-antidiagonal Problem 858. Permute ...

22 days ago

Solved

Return elements unique to either input
Given two numeric inputs a and b, return a row vector that contains the numbers found in only a or only b, but not both. For ex...

22 days ago

Solved

"Low : High - Low : High - Turn around " -- Create a subindices vector
Let two vectors *lo* and *hi* be given. The job is to create a index vector like so idx = [lo(1):hi(1) lo(2):hi(2) ...]...

22 days ago