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Count the primes resulting from changing one digit of a number
If you start with the number 24 and seek primes by changing a single digit, you can find two: 23 and 29. If you start with 130, ...

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Solve an easy binary puzzle
A binary puzzle presents a square grid (or matrix) of cells in which each cell must be 0 or 1. The finished puzzle must follow t...

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Indicate how the Prague astronomical clock strikes the hours
The astronomical clock in Prague has a bell that rings 1, 2, 3, or 4 times. The number of strokes follows the sequence 123432123...

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Convert integers from base 10 to proper primary notation
This problem is the companion to Cody Problem 60782. The proper primary system of expressing non-negative numbers has three digi...

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Convert integers from primary notation to base 10
The primary system of expressing numbers has three digits: m, x, and p, which correspond to -1, 0, and 1. The places in a primar...

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Express integers in negabinary
Negabinary numbers are written in base -2. For example, the negabinary number 11010 is , or 6 in base 10. In a similar way, -3 i...

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Play Hocus Focus
The card game Hocus Focus starts by placing twelve cards with wizards face up on a table. The characteristics of the wizards tha...

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Complete hydraulic geometry relations
Hydraulic geometry relations express the velocity , width , and depth of a river as a function of the discharge (or flow) , whi...

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Bit Stream conversion to Audio Frequency Shift Key using Bell 202 (Modem)
Convert a character binary bit-stream transmitted at a certain baud-rate into an audio stream using Audio Frequency Shift Key (A...

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Determine whether a number is a Ludic prime
Ludic numbers are formed by a sieve. Start with a list of the positive integers. Skip 1 and start with 2. Then delete every seco...

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Find the closest canyon prime
My wife and I celebrated our honeymoon and most recent anniversary in Yellowstone and Grand Teton National Parks. After returnin...

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Sum along each diagonal of a matrix
Write a routine that returns the sums along the diagonals of a given matrix, A, where the first diagonal is the bottom left corn...

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List composite numbers that do not contain their prime factors as substrings
The number 63 has the prime factorization 3, 3, and 7, and it contains one of them (3) as a substring. In contrast, the number 4...

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Build a block Toeplitz matrix
A symmetric block Toeplitz matrix has the form, where the are compatibly-sized matrices. Write a routi...

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Condition number of Kronecker product
Given NxN matrix A and MxM matrix B, where M,N<=1000, write a routine to compute the condition number of kron(A,B).

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TingTing
Output logical "true" if the input is the answer to luck and money$$$. Otherwise, output logical "false".

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Extract diagonal of sparse quadratic form
Consider the matrix A and vector v given by, A=round(sprand(5e3,1e4,1/1e4*100)*100); v=randi(10,width(A),1); Write a rout...

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List Ormiston prime pairs
The numbers 1913 and 1931 form the first Ormiston prime pair. The numbers are consecutive primes, and they are anagrams of each ...

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2x2 binning of a large sparse matrix
Consider the 20000 x 20000 sparse matrix, A=round(sprand(2e4,2e4,1/1e4*100)*1000); The task is to divide this matrix into 2x...

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List the partitions of an integer
Several Cody problems deal with partitions of an integer, or the ways an integer can be written as the sum of positive numbers—...

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Area of a rectangle
FInd the area of a rectangle with a length L and width W. Round to the nearest integer.

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Compute the dispersion coefficient
A contaminant dumped or spilled into a river will move downstream with the flow, but it will also spread in the flow direction b...

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Extend the digamma function to negative arguments
While solving one of Ramon Villamangca’s problems, I needed the value of , where is the digamma function. However, MATLAB’s fun...

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Describe n from right to left
If you were to describe the number 46 from right to left, you could say “one 6, one 4”, or 1614. The number 8663 would be “one 3...

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Find out if the given number is a square of natural number.
For example , Input =4,output =1 Input=1,output=1 Input=0,output=0 Input=8,output=0

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Explore the twin prime Goldbach conjecture
The Goldbach conjecture says that every positive even integer greater than 2 can be expressed as the sum of two prime numbers in...

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Moyenne pondérée
Ecrire une fonction qui prend en entrée un vecteur P et un vecteur V et calcule la moyenne pondérée MP des élements vi d'un vec...

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Conditional transpose II
As in problem 60734, you're given two vectors, x and y, which might be row or a column vectors. Your task is to ensure that y ha...

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Delete some elements in the natural set and find the sum of the first n terms
Delete the number (except 0，1) with a complete square number from the natural set of numbers, form a new set of numbers, find th...

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Conditional transpose
You're given two vectors of the same length, x and y, which might be row or a column vectors. Your task is to ensure that y has ...

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