OFFSET
0,3
COMMENTS
a(p)=2 for prime p.
MATHEMATICA
a29[n_] := a29[n] = (s = If[OddQ[n], 2^((n-1)/2), 2^(n/2-2) + 2^(n/2 - 1)]; a29[0] = 1; Do[s = s + EulerPhi[d] 2^(n/d)/(2n), {d, Divisors[n]}]; s);
a1371[n_] := Sum[MoebiusMu[d] a29[n/d], {d, Divisors[n]}]; a1371[0] = 1;
a[0] = 0; a[n_] := a29[n] - a1371[n];
Array[a, 70, 0] (* Jean-François Alcover, Aug 28 2019 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Valery A. Liskovets, Jan 17 2006
EXTENSIONS
More terms from Jean-François Alcover, Aug 28 2019
STATUS
approved