OFFSET
0,5
LINKS
Antti Karttunen, Table of n, a(n) for n = 0..1024
MATHEMATICA
a[n_] := If[n == 0, 0, Sum[EulerPhi[2d] 2^(n/d) - Boole[OddQ[d]] MoebiusMu[d] 2^(n/d), {d, Divisors[n]}]/(2n)];
Array[a, 66, 0] (* Jean-François Alcover, Aug 29 2019 *)
PROG
(PARI) a(n) = if (n==0, 0, (sumdiv(n, d, eulerphi(2*d) * 2^(n/d)) - sumdiv(n, d, (d%2)*(moebius(d)*2^(n/d))))/(2*n)); \\ Michel Marcus, Oct 21 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Valery A. Liskovets, Jan 17 2006
EXTENSIONS
More terms from Antti Karttunen, Oct 21 2017
STATUS
approved