OFFSET
0,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..2000
MATHEMATICA
a[0]:= 0; a[1]:= 1; a[n_]:= a[EulerPhi[n - 1]] + a[EulerPhi[n - 2]];
Table[a[n], {n, 0, 50}] (* G. C. Greubel, May 29 2018 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Labos Elemer, Jul 22 2002
STATUS
approved