OFFSET
1,4
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
MATHEMATICA
f[1] = 1; f[n_] := f[n] = 1/2 (Sum[Mod[d, 2], {d, Divisors[n]}] - Sum[f[d] f[n/d], {d, Divisors[n][[2 ;; -2]]}]);
a[n_] := IntegerExponent[Denominator[f[n]], 2];
Array[a, 105] (* Jean-François Alcover, Sep 13 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen and Andrew Howroyd, Aug 29 2018
STATUS
approved