MathDB
One of the twins is a prime (BMT 2019 Discrete #6)

Source:

May 25, 2019
number theoryprime numbers

Problem Statement

Define f(n)=n2+n2 f(n) = \dfrac{n^2 + n}{2} . Compute the number of positive integers n n such that f(n)1000 f(n) \leq 1000 and f(n) f(n) is the product of two prime numbers.