As I was going to St. Ives I met a man with seven wives,
Each wife had seven sacks, each sack had seven cats,
Each cat had seven kits: kits, cats, sacks and wives,
How many were going to St. Ives?
OK, here's one for real: show that for any natural number n, the
A = 2903^n - 803^n - 464^n + 261^n
is a multiple of 1897.