If a multiple of a prime, say 13, occurs in Sylvester's sequence, then Sylvester's sequence modulo that prime eventually gets stuck on a bunch of 1's, and
FixedPoint would catch that: 2, 3, 7, 4, 0, 1, 1, 1, ... But with 5, which is 2, 3, over and over again,
FixedPoint would get the system stuck on an infinite loop, right?
So how do you catch that first repeated term if the sequence enters a period of length greater than 1?