OFFSET
0,4
FORMULA
EXAMPLE
n=10: 10! = 3628800; trajectory ={3628800, 5702400, 5702400, ...} a(10) = 2, one transient and 1 cycle term.
MATHEMATICA
fs[x_]:=EulerPhi[DivisorSigma[1, x]] itef[x_, len_]:=NestList[fs, x, len] Table[Length[Union[itef[w!, 1000]]], {w, 0, 16}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Labos Elemer, Jul 22 2004
STATUS
approved