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Easy Sequences 12: 50th Prime
Write a function that outputs the th prime after a given number . For example, the th prime after is . NOTE: If itself is pr...

3 years ago

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Easy Sequences 10: Sum of Cumsums of Fibonacci Sequence
The function F(n) is defined as the set of Fibonacci numbers from the first up to the n-th. S(n) is the result of applying to F,...

3 years ago

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Easy Sequences 9: Faithful Pairs
A "faithful number" is a non-prime number that is one less or one more than some prime number but not both. For example, for num...

3 years ago

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Easy Sequences 5: Project Euler Problem 1 - Again!
We are all familiar with Project Euler Problem 1. This time let's try it on bigger multiples and larger range. Find the sum of ...

3 years ago

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Easy Sequences 6: Coefficient sums of derivatives
Consider the polynomial function and its first-order derivative . The sums of the coefficients of P and P', are and , respecti...

3 years ago

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Easy Sequences 11: Factorial Digits without Trailing Zeros
Here is an easy one... It is not difficult to count the number of digits of the factorial of a given number. For example for 'n...

3 years ago

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Easy Sequences 4: Eliminate the Days of Confusion
If a date is written in purely numeric format some dates can be confusing, if we don't know the date format used. For example, "...

3 years ago

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Easy Sequences 3: Prime 44-number Squares
The positive integers 62 and 238 are related. Their squares (3844 and 56,644) both end in '44'. In fact, 62 and 238 are the 3rd ...

3 years ago

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Easy Sequences 2: Trigonometric function with integral input and output
The function 'F', defined as: , will always return an integer if the input is a natural number (in radian...

3 years ago

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Easy Sequences 1: Find the index of an element
The nth element of a series is defined by: . Obviously, the first element . Given the nth element , find the value of the corre...

3 years ago

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Optimum Egyptian Fractions
Following problem was inspired by <http://www.mathworks.com/matlabcentral/cody/problems/2126-split-bread-like-the-pharaohs-egypt...

3 years ago

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Determine whether a number is practical
A number is practical if all smaller numbers can be written as a sum of the proper divisors of . The number 24 is practical bec...

3 years ago

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How many days does the cat take to climb out of the hole?
A cat accidentally falls down a hole with sloping but rough sides. It can climb out of the hole of height h metres, but for ever...

3 years ago

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Tribute to Ramanujan
The nth taxicab number, denoted as T(n), is defined as the smallest number that can be expressed as a sum of two positive algebr...

3 years ago

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Largest Geometric Series
Extension of Ned Gulley's wonderful Problem 317. In a geometric series, ratio of adjacent elements is always a constant value. ...

3 years ago

Answered
Removing duplicate rows (not "unique")
%Here's a much cleaner way to do it with 2019a or later! [B,BG]=groupcounts(A); A_reduced=BG(B==1); % or just A if you want th...

3 years ago | 0

Solved

Leftovers? Again?!
I am thinking of a positive number X. To determine what number I am thinking of, I will give you two 1xN vectors. The first ve...

3 years ago

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Sum of all the divisors of n

3 years ago

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Prime Ladders
A <http://en.wikipedia.org/wiki/Word_ladder word ladder> transforms one word to another by means of single-letter mutations. So ...

3 years ago

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Factorions: Numbers that equal the sum of the factorials of their digits
From Wikipedia: _A factorion is a natural number that equals the sum of the factorials of its decimal digits_ For example: ...

3 years ago

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Dudeney Numbers: Numbers which are the cube of their decimal sum
From Wikipedia: _A Dudeney number is a positive integer that is a perfect cube such that the sum of its decimal digits is equa...

3 years 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...

3 years ago

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Pandigital number n°3 (Inspired by Project Euler 32)
After Problem 2319 and 2320. An n-digit number is pandigital if it makes use of all the digits 1 to n exactly ONCE. For examp...

3 years ago

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Pandigital number n°2 (Inspired by Project Euler 32)
After <http://www.mathworks.com/matlabcentral/cody/problems/2319 Problem 2319>. An n-digit number is pandigital if it makes u...

3 years ago

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Pandigital number n°1 (Inspired by Project Euler 32)
A little warm-up to begin... An n-digit number is pandigital if it makes use of all the digits 1 to n exactly ONCE. For ex...

3 years ago

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is the number happy?
test is a given integer number is Happy of not? answer 1 if yes or 0 is no

3 years ago

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Find all vampire fangs
A <http://en.wikipedia.org/wiki/Vampire_number vampire number> is a number v that is the product of two numbers x and y such th...

3 years 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 ...

3 years ago

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Make a Pandiagonal Prime Magic Square: 11 x 11
This Fun with Primes Challenge is to create a Pandiagonal Prime Magic Square of size 11x11 given eleven APk sequences with 10 co...

3 years ago

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Pandiagonal Prime Magic Square Verification
Verify if an NxN matrix is a Pandiagonal Prime Magic Square. Required properties: 1) N^2 prime values ( No repeats, 1 ...

3 years ago