MathDB
Putnam 1977 A5

Source:

April 7, 2022
college contests

Problem Statement

Prove that (papb)=(ab)(mod p)\binom{pa}{pb}=\binom{a}{b} (\text{mod } p) for all integers p,a,p,a, and bb with pp a prime, p>0,p>0, and a>b>0.a>b>0.