Multiplicative

[David Wilson]

A023153 through A023161 are all multiplicative.

Basically, if gcd(x, y) = 1, we can use the Chinese remainder theorem to 
induce a bijection between pairs of cycles modulo x and y to cycles modulo 
xy.  This means a(xy) = a(x)a(y), and a is multiplicative.  This argument 
works for cycles of any injection f: Z(n) -> Z(n), including f(n) = n^k, as 
in these sequences.

a(p^k) is difficult.