OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..160
N. J. A. Sloane, Transforms
FORMULA
a(n) ~ n! / (2*(log(2))^(n+1)). - Vaclav Kotesovec, Aug 25 2014
MAPLE
with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d, j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: f:= proc(n) option remember; local k; if n<=1 then 1 else add(binomial(n, k) *f(n-k), k=1..n) fi end: aa:= etr(k->f(k-1)): a:= n->aa(n+1): seq(a(n), n=0..30); # Alois P. Heinz, Sep 08 2008
MATHEMATICA
etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n-j], {j, 1, n}]/n]; b]; f[n_] := f[n] = If[n <= 1, 1, Sum[Binomial[n, k]*f[n-k], {k, 1, n}]]; aa := etr[f[#-1]&]; a[n_] := aa[n+1]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 10 2014, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Alois P. Heinz, Sep 08 2008
STATUS
approved