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List the Moran numbers
The quotient of a Moran number and its digit sum is prime. For example, 117 and 481 are Moran numbers because 117/(1+1+7) is 13 ...

fast 2 Jahre vor

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List the cuban primes
The number 61 is a cuban prime because it is prime and the difference two cubes, 64 and 125. Write a function to list the cuba...

fast 2 Jahre vor

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List the semiprimes
A semiprime number—or a 2-almost prime—is the product of two prime numbers. The numbers and are semiprimes, but and are not....

fast 2 Jahre vor

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Compute the bubble popper fidget spinner sequence
A fidget spinner is a toy made of multiple lobes that pivot on a ball bearing. In some, the lobes hold bubble poppers, or rubber...

fast 2 Jahre vor

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Factor a number into Fermi-Dirac primes
Cody Problem 58018 asked you to list the Fermi-Dirac primes, which are prime powers with exponents that are powers of 2. As note...

fast 2 Jahre vor

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List the Fermi-Dirac primes
The Fermi-Dirac “primes” are prime powers with exponents that are powers of 2. The first nine terms of the sequence are 2, 3, 4,...

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Identify de Polignac numbers
The numbers 125 and 329 can be written as the sum of a prime and a power of 2. For example, , and . The numbers 127 and 331, whi...

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List numbers such that every sum of consecutive positive integers ending in those numbers is composite
The sequence in question in this problem involves numbers such that all sums of consecutive positive integers ending with are ...

fast 2 Jahre vor

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List the two-bit primes
Each year at Christmas, my father-in-law and his partner send me the Puzzle Mania section from the New York Times. This year’s e...

fast 2 Jahre vor

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Solve an equation involving primes and fractions
Write a function to find pairs of primes and satisfying the equation where is an integer. The function should take a numbe...

fast 2 Jahre vor

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List odd twin composites
Twin primes, or prime numbers that differ by 2 (e.g., 17 and 19, 59 and 61, or 191 and 193), are the subject of several Cody pro...

fast 2 Jahre vor

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List the Beatriz numbers
Write a function to find integers less than or equal to an input value that solve the equation . The function gives the sum o...

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List the Euclid numbers
Euclid proved that the number of primes is infinite with the following argument. Suppose the primes form a finite set , , . Comp...

fast 2 Jahre vor

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Create Combination
Motivation: In many problems, we need to create combinations with the function nchoosek. In some cases, however, choices are lim...

mehr als 2 Jahre vor

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Usage of java.math : N Choose K with unlimited precision
Calculate the binomial coefficient nchoosek with full accuracy. This challenge may use the wonderful word of java.math that allo...

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Get ranking of a combination looking for speed.
I have the numbers pulled without replacement from the set [1 2 3 4 5 6 7 8 9 10 11 12 13]; They are then ordered from least to...

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Get ranking of a combination
I have the numbers pulled without replacement from the set [1 2 3 4 5 6 7 8 9 10 11 12 13]; They are then ordered from least to ...

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Put m balls into n boxes (again)
According to Cody Problem 1516, if I put 3 balls into 2 boxes then 1 1 1 1 1 2 1 2 2 ...

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Put m balls into n boxes
Can you find all the cases where, if I put 3 balls into 2 boxes the case is 1 1 1 1 1 2 1 ...

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Numbered lottery balls into cells
You are running a lottery, and have a number of different balls numbered 1 to N. Your job is to figure out how many different w...

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A (wrong) place for everything, and everything in its (wrong) place
You have an equal number of cups and balls, each labelled from one to N. You randomly place one ball in each cup. Determine th...

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Possible Outcomes of American Roulette
The payout for American roulette can be calculated by: payout = (38/n)-1 where n is the number of squares the bet covers. ...

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NCHOOSEK - Time Optimization
Input V —— Set of all choices, a vector of N, 1 < N < 100 K —— Number of selected choices, a scalar, 0 <= K <= N Output C ——...

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Combinations without using nchoosek
You have to generate a matrix with all possible combinations of n elements *taken 2* at a time, *without using nchoosek(1:n,2)* ...

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Which permutation is it?
Let write some permutations of positive integers. 1: 1 2 3 4 5 6 ... 2: 2 1 3 4 ... 3: 1 3 2 4 ....

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N-th permutation.
Let write some permutations of positive integers. 1: 1 2 3 4 5 6 ... 2: 2 1 3 4 ... 3: 1 3 2 4 ... ...

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Diophantine Equations (Inspired by Project Euler, problem 66)
Consider the quadratic Diophantine equation of the form: x^2 – Dy^2 = 1 When D=13, the minimal solution in x is 649^2 – 13...

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High Precision Square Root (Inspired by Project Euler 80)
Given a positive integer n which is not a perfect square, write a MATLAB script that will calculate the square root of n truncat...

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Decrypt the cypher using XOR encryption (for beginners)
Inspired by Project Euler n°59 Each character on a computer is assigned a unique code and the preferred standard is ASCII (...

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I've got the power! (Inspired by Project Euler problem 29)
Consider all integer combinations of a^b and b^a for the integer values 2 ≤ a ≤ 4 and 2 ≤ b ≤ 5: 2^2=4, 2^3=8, 2^4=16,...

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