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Sieve of Eratosthenes
Find the nth lucky prime number. <https://planetmath.org/luckyprime> can u find a way for large n?

4 years ago

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Integer complexity (Large numbers)
Inspired by <http://www.mathworks.com/matlabcentral/cody/problems/42831-integer-complexity Problem 42831>, this problem aims to ...

4 years ago

Solved

Integer complexity
Given an array, n, of positive integers, return an array, c, of the same size, in which each element is the <https://en.wikipedi...

4 years ago

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Number of even divisors of a given number
Given a Number n, return the number of its even divisors without listing them. example: n=14 ; EvenDivisors={2,14} ; y=2 ...

4 years ago

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Lunar Arithmetic (Addition)
<https://oeis.org/A087061 OEIS link for a description of lunar arithmetic> Simply take the larger digit. Example 1: ...

4 years ago

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Whole Number Un-Concatenator
Write a function that accepts an integer and an index digit and returns a vector containing two integers which are the leading a...

4 years ago

Solved

Better Index Number
Let's say you want to save many, many files and append these files with a certain sortable index number. As you probably know, y...

4 years ago

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The last non-zero digit of a factorial
For given positive integer n, what is the last non-zero digit of n!? Example: factorial(11) = 39916800 Last non-zero d...

4 years ago

Problem

Easy Sequences 53: Greatest Proper Divisor
The greatest proper divisor () of an integer is the largest integer , such that and . Furthermore, we define: . Below is the...

4 years ago | 3 | 6 solvers

Solved

The number of trailing zero digit of a factorial
For given positive integer n, take factorial of that number. How many trailing zeros does it have? Example: factorial(11) = 3...

4 years ago

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How brilliant are you?
A Brilliant number is defined as a number with two prime factors, both of which have the same number of digits. Some examples: ...

4 years ago

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Find two triangular numbers whose sum is input.
Find two triangular numbers whose sum is _input_. Note: The difference beetween the triangular numbers should be minimum.

4 years ago

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Gapful numbers
If a number is divisible by the number formed by the first and last digit of that number then it is defined as a gapful number. ...

4 years ago

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Check if the input is an interprime

4 years ago

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Compute the Euler totient function

4 years ago

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Recursion at variable input
input of any length a =2 b =2 c =3 output = (a^b)^c = 64

4 years ago

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Maximum of ND-array
Find the maximum element of a N dimensional array. Example: A=[1 2 4 ; -20 4 10]; The maximum is 10.

4 years ago

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Convert decimal to binary and then generate the minimum binary it can with jumbling
input is 10 --> 1010 output should be 3 --> 0011 input 23 --> 10111 output should be 15 --> 01111

4 years ago

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Zero Cross
Write a function that counts the number of times n a signal x changes sign. Examples x = [1 2 -3 -4 5 6 -7 8 -9 10 11] ...

4 years ago

Solved

Weave two matrices together to form one matrix
Take the first column from matrix a, then insert the first column from matrix b, and so on. For example: a = [1 2 3 4]; b ...

4 years ago

Solved

S-T-R-E-T-C-H I-T O-U-T
You will be given a row of numbers (x), and a single number (n). Your job is to write a script that will stretch out the row of...

4 years ago

Solved

Find the sum of the elements in the "second" diagonal
Find the sum of the elements in the diagonal that starts at the top-right corner and ends at the bottom-left corner.

4 years ago

Solved

Flip the diagonal values
Write a program that flip the elements of main diagonal , upper and lower diagonal values of a sqare matrix. For example if a ...

4 years ago

Problem

Easy Sequences 52: Non-squarable Rectangles
Any integer-sided rectangle can be cut into unit rectangles () and rearranged into sets of smaller rectangles. For example the ...

4 years ago | 2 | 5 solvers

Problem

Easy Sequences 51: Positive Gaussian Primes
A Gaussian Prime is a gaussian integer that cannot be decomposed as product of two non-unit gaussian integers (the complex units...

4 years ago | 2 | 6 solvers

Solved

Special Relativity 101.
Special relativity states that the effective mass of an object varies as a function of its velocity. If *c* is the speed of ligh...

4 years ago

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Double Deal
*Description* Given an input vector _v_, return the first element as the first output, the second element as the second outpu...

4 years ago

Solved

Primes for Large N: 2^30, System Memory Limit
This Challenge is to further improve the "primes" function for speed/memory usage to the Limit of Cody Memory. The Matlab fun...

4 years ago

Solved

Count from 0 to N^M in base N.
Return an array of numbers which (effectively) count from 0 to N^M-1 in base N. The result should be returned in a matrix, with ...

4 years ago

Solved

count to vector
Return a matrix of numbers of dimension K by N, where K = prod(v), and N=length(v). The rows count from a vector of ones up to v...

4 years ago