MathDB
D 4

Source:

May 25, 2007
modular arithmeticblogsCongruences

Problem Statement

Let nn be a positive integer. Prove that nn is prime if and only if (n1k)(1)k(modn){{n-1}\choose k}\equiv (-1)^{k}\pmod{n} for all k{0,1,,n1}k \in \{ 0, 1, \cdots, n-1 \}.