A283844 a(n) = A063776(2*n) + 1.

3, 5, 13, 33, 105, 345, 1173, 4097, 14573, 52433, 190653, 699073, 2581113, 9586985, 35791473, 134217729, 505290273, 1908874585, 7233629133, 27487790721, 104715393913, 399822410105, 1529755308213, 5864062017537, 22517998136937, 86607685141745

Offset: 1

Author

N. J. A. Sloane, Mar 28 2017

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Juhani Karhumäki, S. Puzynina, M. Rao, M. A. Whiteland, On cardinalities of k-abelian equivalence classes, arXiv preprint arXiv:1605.03319 [math.CO], 2016.

Crossrefs

Cf. A063776.

A bisection of A283843.

Programs

Mathematica

Table[a=Select[Divisors[n], OddQ[#]&]; (1 + Apply[Plus, 2^(n/a)EulerPhi[a]]/n), {n, 2, 52, 2}] (* Vincenzo Librandi, Mar 29 2017 *)

PARI

a(n) = my(m = 2*n); 1 + sumdiv(m, d, (d%2)* 2^(m/d)*eulerphi(d))/m; \\ Michel Marcus, Aug 18 2018

Formula

See Karhumäki et al. (2016), Proposition 7.4.