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Guess Cipher
Guess the formula to transform strings as follows: 'Hello World!' --> 'Ifmmp Xpsme!' 'Can I help you?' --> 'Dbo J ifm...

2 months ago

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Extra safe primes
Did you know that the number 5 is the first safe prime? A safe prime is a prime number that can be expressed as 2p+1, where p is...

2 months ago

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Pentagonal Numbers
Your function will receive a lower and upper bound. It should return all pentagonal numbers within that inclusive range in ascen...

2 months ago

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Amicable numbers
Test whether two numbers are <https://en.wikipedia.org/wiki/Amicable_numbers amicable>, meaning that the sum of the proper divis...

2 months ago

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P-smooth numbers
This Challenge is to find <https://en.wikipedia.org/wiki/Smooth_number P-smooth number> partial sets given P and a max series va...

2 months ago

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Iccanobif numbers 1
There are a lot of problems in Cody that deal with Fibonacci numbers (1, 1, 2, 3, 5, 8, 13, 21 etc...) so let's turn things arou...

2 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...

2 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 ...

2 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...

2 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...

2 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...

2 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>.

2 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 ...

2 months ago

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Last non-zero digit
Given a number n, find the last non-zero digit of the factorial of that number. You need to take care of the large values of n....

2 months ago

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Champernowne Constant
The <http://en.wikipedia.org/wiki/Champernowne_constant Champernowne constant> is a real number whose digits in decimal represen...

2 months ago

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Is it an Armstrong number?
An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. Fo...

2 months ago

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Golomb's self-describing sequence (based on Euler 341)
The Golomb's self-describing sequence {G(n)} is the only nondecreasing sequence of natural numbers such that n appears exactly G...

2 months 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...

2 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...

2 months ago

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Ordinal numbers
Given an integer n, return the corresponding ordinal number as a character string. For example, ord(1)='1st' ord(2)=...

2 months ago

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Determine if input is a perfect number
A perfect number occurs whent the sum of all divisors of a positive integer, except the number itself, equals the number. Examp...

2 months ago

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Determine if input is a Narcissistic number
<http://en.wikipedia.org/wiki/Narcissistic_number Narcissistic number> is a number that is the sum of its own digits each raised...

2 months ago

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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...

2 months ago

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Mersenne Primes
A Mersenne prime is a prime number of the form M = 2^p - 1, where p is another prime number. For example, 31 is a Mersenne prim...

2 months 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 ...

2 months ago

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Woodall number
Test whether the input is a Woodall number: <http://en.wikipedia.org/wiki/Woodall_number> _Please do not cheat by simply chec...

2 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...

2 months 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...

2 months ago

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Balanced number
Given a positive integer find whether it is a balanced number. For a balanced number the sum of first half of digits is equal to...

2 months ago

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Fangs of a vampire number
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 ...

2 months ago