A073174 a(n) = a(phi(n-1)) + a(phi(n-2)), a(0)=0, a(1)=1.

0, 1, 1, 2, 2, 2, 3, 3, 4, 5, 5, 5, 7, 7, 9, 10, 7, 8, 11, 10, 14, 15, 11, 12, 16, 15, 18, 21, 18, 18, 25, 22, 29, 32, 21, 21, 23, 23, 30, 34, 27, 23, 34, 34, 41, 48, 30, 27, 41, 37, 41, 48, 43, 45, 59, 54, 38, 43, 39, 41, 57, 46, 64, 82, 48, 52, 70, 55, 84, 99, 70, 57, 86, 86, 102

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

Cf. A000010.

Sequence in context: A029114 A224710 A210469 * A107631 A029098 A074286

Adjacent sequences: A073171 A073172 A073173 * A073175 A073176 A073177

Keyword

easy,nonn

Author

Labos Elemer, Jul 22 2002

Status

approved