From minus one and its square root, via cyclic, weird, amicable,
perfect, untouchable and lucky numbers, aliquot sequences, the Cattle
problem, Pascal's triangle and the Syracuse algorithm, music, magic and
maps, pancakes, polyhedra and palindromes, to numbers so large that they
can boggle the imagination, all you ever wanted to know about numbers is
here. There is even a comprehensive index for those annoying occasions
when you remember the name but can't recall the number. Kaprekar number?
Ah, yes, of course...