A100427 Bisection of A000081 (odd part).

1, 2, 9, 48, 286, 1842, 12486, 87811, 634847, 4688676, 35221832, 268282855, 2067174645, 16083734329, 126186554308, 997171512998, 7929819784355, 63411730258053, 509588049810620, 4113254119923150, 33333125878283632, 271097737169671824, 2212039245722726118

Offset: 0

Author

N. J. A. Sloane, Nov 20 2004

Keywords

• nonn
• easy

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..400

Crossrefs

Cf. A000081, A100034, A299113.

Programs

Maple

with(numtheory):
b:= proc(n) option remember; local d, j; `if`(n<2, n,
      (add(add(d*b(d), d=divisors(j))*b(n-j), j=1..n-1))/(n-1))
    end:
a:= n-> b(2*n+1):
seq(a(n), n=0..50);  # Alois P. Heinz, May 16 2013

Mathematica

b[n_] := b[n] = If[n <= 1, n, Sum[Sum[d*b[d], {d, Divisors[j]}]*b[n-j], {j, 1, n-1}]/(n-1)]; a[n_] := b[2*n+1]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 19 2014, after Alois P. Heinz *)

Extensions

More terms from Joshua Zucker, May 12 2006