theorem Th34: :: NUMBER02:34

for n being Nat holds
( not 6 divides n iff ex k being Nat st
( n = (6 * k) + 1 or n = (6 * k) + 2 or n = (6 * k) + 3 or n = (6 * k) + 4 or n = (6 * k) + 5 ) )