OFFSET
1,3
COMMENTS
a(2^k)=1 for all k including k=0.
a(p)=2, a(2p)=3, a(4p)=11, etc. for an odd prime p.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..6300
R. W. Hall and P. Klingsberg, Asymmetric Rhythms, Tiling Canons and Burnside's Lemma, Bridges Proceedings, pp. 189-194, 2004 (Winfield, Kansas).
R. W. Hall and P. Klingsberg, Asymmetric Rhythms and Tiling Canons, Preprint, 2004; The American Mathematical Monthly, Volume 113, 2006 - Issue 10, [alternative link].
MATHEMATICA
A006575[n_] := DivisorSum[n, If[BitAnd[#, 1] == 1, MoebiusMu[#] (3^(n/#) - 1), 0]&]/(2n);
A115114[n_] := Sum[EulerPhi[2d] + Boole[OddQ[d]] EulerPhi[d] 3^(n/d), {d, Divisors[n]}]/(2n);
Array[a, 60] (* Jean-François Alcover, Aug 29 2019 *)
PROG
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Valery A. Liskovets, Jan 17 2006
EXTENSIONS
More terms from Antti Karttunen, Jan 19 2020
STATUS
approved