To put it algebraically, n ! ≡ − 1 mod p {\displaystyle n!\equiv -1\mod p} but p ≢ 1 mod n {\displaystyle p\not \equiv 1\mod n} .
För att uttrycka det algebraiskt, n ! ≡ − 1 mod p {\displaystyle n!\equiv -1\mod p} men p ≢ 1 mod n {\displaystyle p\not \equiv 1\mod n} .