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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...

8 months ago

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Circular Primes (based on Project Euler, problem 35)
The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime. The...

8 months ago

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The Goldbach Conjecture
The Goldbach conjecture asserts that every even integer greater than 2 can be expressed as the sum of two primes. Given the eve...

8 months ago

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Project Euler: Problem 7, Nth prime
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the Nth prime numb...

8 months ago

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Determine if a Given Number is a Triangle Number
*Description:* Determine if the elements of an input array are triangle numbers and return the result as an array with the sa...

8 months ago

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Parasitic numbers
Test whether the first input x is an n-parasitic number: <http://en.wikipedia.org/wiki/Parasitic_number>. ( _n_ is the second in...

8 months ago

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Kaprekar numbers
Test if the input is a Kaprekar number: <http://mathworld.wolfram.com/KaprekarNumber.html>. Return a logical true or false. ...

8 months ago

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Polygonal numbers
The task of <http://www.mathworks.co.uk/matlabcentral/cody/problems/5 Problem 5> is to calculate triangular numbers. By playing ...

8 months ago

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Narcissistic number ?
Inspired by Problem 2056 created by Ted. In recreational number theory, a narcissistic number is a number that is the sum of ...

8 months ago

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Polite numbers. N-th polite number.
A polite number is an integer that sums of at least two consecutive positive integers. For example _7 = 3+4_ so 7 is a polite...

8 months ago

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Polite numbers. Politeness.
A polite number is an integer that sums of two or more consecutive positive integers. Politeness of a positive integer is a num...

8 months ago

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Evil Number
Check if a given natural number is evil or not. Read more at <https://oeis.org/A001969 OEIS>.

8 months ago

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N-th Odious
Given index n return n-th <https://oeis.org/A000069 odious number>.

8 months ago

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Find vampire numbers
A vampire number is a number v that is the product of two numbers x and y such that the following conditions are satisfied: at ...

8 months ago

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Compute Fibonacci Number
Compute the n-th Fibonacci Number f(0) = 0, f(1) = 1, f(2) = 1, f(3) = 2, ... f(42) = 267914296

8 months ago

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nth Rational Number
Return the nth rational number. This is the inverse to Problem 1471. Index of a Rational number The first ten positive rationa...

8 months ago

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Armstrong Number
Determine whether the given input n-digit number is Armstrong Number or not. Return True if it is an Armstrong Number. An n-Dig...

8 months ago

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Generate a Parasitic Number
This problem is the next step up from Problem 156. Rather than determining if an input is a parasitic number, you will be asked ...

8 months ago

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Smith numbers
Return true if the input is a Smith number in base ten. Otherwise, return false. Read about Smith numbers at http://en.wikipedia...

9 months ago

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Is this number Munchhausen?
In this problem, simply return 1 if a supplied number is Munchhausen or 0 if not. Example 153 is narcissistic but not a Munchh...

9 months ago

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Bell Number calculator
Calculate a vector of Bell numbers for sets up to length n. Bell numbers are the maximum number of partitions of a set. See the ...

9 months ago

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Find the 9's Complement
Find the 9's complement of the given number. An example of how this works is <http://electrical4u.com/9s-complement-and-10s-c...

9 months ago

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Day counter function
Write a function called day_counter that returns the number of Mondays that fell on the first day of the month in a given year b...

9 months 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...

9 months ago

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Odd elimination
Inspired by Project Euler problem #539 You'll be given a vector from 1 to n; Going from left to right, remove the first n...

9 months ago

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It's going down. We're finding simbers!
This problem is inspired by Project Euler 520: Simbers. "We define a simber to be a positive integer in which any odd digit, ...

9 months ago

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Pandigital Multiples of 11 (based on Project Euler 491)
A "Pandigital number of order X" is one that contains all of the numbers from 0 to X, but with no leading zeroes. If X>9, the cy...

9 months ago

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Pandigital Factors (Based on Euler 491)
A Pandigital Number is a number containing all of the digits from 0-9 inclusive, with the added stipulation that it does not hav...

10 months ago

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Pseudo Square Root (Inspired by Project Euler 266)
Shamelessly copied from the Project Euler page for Problem 266: ------------- The divisors of 12 are: 1,2,3,4,6 and 12. T...

10 months ago

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Project Euler 249: Prime Subset Sums
Inspired by Problem 249 of Project Euler. <https://projecteuler.net/problem=249> Let S = {2, 3, 5, ...} be the set of prime ...

10 months ago