A positive integer n is the sum of two integer squares iff every prime p ≡ 3 (mod 4) occurs to an even power in its factorisation. Fermat 1640 conjecture, Euler 1749 proof. Primes themselves: p = 2 and p ≡ 1 (mod 4) are uniquely…
A positive integer n is the sum of two integer squares iff every prime p ≡ 3 (mod 4) occurs to an even power in its factorisation. Fermat 1640 conjecture, Euler 1749 proof. Primes themselves: p = 2 and p ≡ 1 (mod 4) are uniquely…