MathDB
2013 HMMT Guts #7: Divisors of 15!

Source:

March 26, 2013
HMMTnumber theoryprime factorization

Problem Statement

Find the number of positive divisors dd of 15!=15142115!=15\cdot 14\cdot\cdots\cdot 2\cdot 1 such that gcd(d,60)=5\gcd(d,60)=5.