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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...

3 months ago

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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...

3 months ago

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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...

3 months ago

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Compute a nested cube root
Consider the quantity . Write a function to compute without using loops or recursion.

3 months ago

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Compute the largest number whose prime factors sum to n
This problem deals with a sequence whose tenth term is 36 because the prime factors of 36 (2, 2, 3, 3) sum to 10. The number 32 ...

3 months ago

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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...

3 months ago

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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 ...

3 months ago

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Play Outside In with primes
In the word game Outside In,* you start with a word, take the first and last letters, try to think of a word in which the two le...

3 months ago

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List the nth prime quartet prefix
Prime numbers larger than 5 can end only in 1, 3, 7, or 9, but of course not all numbers ending in these four digits are prime. ...

3 months ago

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List the delete-a-digit primes

3 months ago

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Solve the arithmetic differential equation D(n) = n

3 months ago

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Compute the arithmetic derivative of integers

3 months ago

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List composite numbers that cannot be written as the sum of two primes

3 months ago

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Find pairs of primes with the same digit sum and a specified separation

3 months ago

Solved

Compute a sum involving the zeta function
Write a function to compute the sum for , where is the zeta function, the subject of Cody Problems 45939, 45988, and 45997.

3 months ago

Solved

Count the primes in Collatz sequences
Several Cody problems (21, 69, 42937, 44448, 44784, 52422) involve Collatz sequences. These start with a seed . If is odd, the ...

3 months ago

Solved

Count block fountains
A block fountain consists of rows of circles in which each row is a continuous block of circles (i.e., adjacent circles are tang...

3 months ago

Solved

Determine whether a number is unprimeable
The number 204 is unprimeable because no single digit can be changed to make it prime. In contrast, the number 207 is not unprim...

3 months ago

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List the nth term of Rozhenko’s inventory sequence
Consider a sequence constructed by repeated inventories. A new inventory begins each time a zero is encountered. The first few i...

3 months ago

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List prime anagrams of a number

3 months ago

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Find the smallest prime with n inside
Consider the sequence that begins 101, 113, 127, 131, 149, 151, 163,... Not only is every term prime, the th term is the smalles...

3 months ago

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Identify prime words

3 months ago

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List Honaker primes
The number 131 is the 32nd prime number. It is a Honaker prime because the sum of its digits (1+3+1) equals the sum of the digit...

3 months ago

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Label primes with the Erdos-Selfridge classification

3 months ago

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List Proth primes

3 months ago

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Compute home primes in a given base

3 months ago

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Determine whether a number is a prime self number
Integers can be classified as generated numbers or self numbers. A generated number is one that can be expressed as the sum of a...

3 months ago

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List the good primes
The th prime is classified as “good” if for . For example, 5 is a good prime because is greater than and , but 7 is not beca...

3 months ago

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List the dihedral primes
The number 1880111 is a dihedral prime (or dihedral calculator prime) because on a seven-segment display it is prime (a) forward...

3 months ago

Solved

Multivariate polynomials - convert monomial form to array
In <https://www.mathworks.com/matlabcentral/cody/problems/44259-product-of-two-multidimensional-polynomials Problem 44259> I ask...

3 months ago