OFFSET
1,3
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..200
FORMULA
a(n) = Sum_{d|n} mu(n/d) * A084423(d).
MATHEMATICA
u[0, _] = 1; u[k_, j_] := u[k, j] = Sum[Binomial[k - 1, i - 1]*DivisorSum[j, u[k - i, j]*#^(i - 1)&], {i, 1, k}];
b[0] = 1; b[n_] := DivisorSum[n, EulerPhi[#]*u[n/#, #]&]/n;
a[1] = 1; a[n_] := DivisorSum[n, MoebiusMu[n/#]*b[#]&];
Array[a, 26] (* Jean-François Alcover, Jun 16 2017, using Franklin T. Adams-Watters' code for A084423 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 09 2017
STATUS
approved