Problem 53740. Easy Sequences 59: Almost Twin Primes
A positive integer pair , is called an "almost twin prime pair", if one of the pair is a prime and the other is either a prime or a semiprime. A semiprime is a natural number that is a product of only two and exactly two not necessarily distinct prime numbers (e.g. 4, 6, 9, , , , , , ...).
Listed below are all almost twin prime pairs with no element greater than :
Our task in this exercise is, to create a function that counts the number of almost twin prime pairs whose elements are less than or equal to a given limit Therefore for , our function should return .
Solution CommentsShow comments
Problem Recent Solvers3