This man proposed that every positive integer is a sum of at most three triangular numbers, four square numbers, and, in general, n n-polygonal numbers.  He also noted that the area of a rational right triangle cannot be a square number.  His primes are of the form 2-to-the-2-to-the-n plus 1 for integer n, and his "little theorem" states that if p is a prime number and q is a natural number, q-to-
This man proposed that every positive integer is a sum of at most three triangular numbers, four square numbers, and, in general, n n-polygonal numbers.  He also noted that the area of a rational right triangle cannot be a square number.  His primes are of the form 2-to-the-2-to-the-n plus 1 for integer n, and his "little theorem" states that if p is a prime number and q is a natural number, q-to-the-p is q mod p.  FTP identify the French mathematician best known for a marginal notation in his copy of Diophantus' Arithmetica.
This man proposed that every positive integer is a sum of at most three triangular numbers, four square numbers, and, in general, n n-polygonal numbers.  
Pierre de Fermat