gcd(3,7) = 1
gcd(6,9) = 3
gcd(9,11) = 1
gcd(12,13) = 1
gcd(15,15) = 15
gcd(18,17) = 1
gcd(21,19) = 1
gcd(24,21) = 3
gcd(27,23) = 1
gcd(30,25) = 5
gcd(33,27) = 3
gcd(36,29) = 1
gcd(39,31) = 1
gcd(42,33) = 3
gcd(45,35) = 5
gcd(48,37) = 1
gcd(51,39) = 3
gcd(54,41) = 1
gcd(57,43) = 1
gcd(60,45) = 15
gcd(63,47) = 1
gcd(66,49) = 1
gcd(69,51) = 3
gcd(72,53) = 1
gcd(75,55) = 5
gcd(78,57) = 3
gcd(81,59) = 1
gcd(84,61) = 1
gcd(87,63) = 3
gcd(90,65) = 5
gcd(93,67) = 1
gcd(96,69) = 3
gcd(99,71) = 1