OFFSET
1,2
EXAMPLE
96 => 63 => 91 => 195 => 252 => 195 => ..., therefore 195 and 252 are in the sequence.
MATHEMATICA
a = {}; f[n_] := DivisorSigma[1, EulerPhi[ n]]; Do[ AppendTo[ a, NestWhileList[f, n, UnsameQ, All][[ -1]]]; a = Union[a], {n, 10^6}]; Take[ a, 43] (* Robert G. Wilson v, Jul 21 2004 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 19 2004
EXTENSIONS
Edited, corrected and extended by Robert G. Wilson v, Jul 21 2004
STATUS
approved