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%I #16 Feb 02 2018 17:00:34
%S 0,1,4,20,115,719,4766,32973,235381,1721159,12826228,97055181,
%T 743724984,5759636510,45007066269,354426847597,2809934352700,
%U 22409533673568,179655930440464,1447023384581029,11703780079612453,95020085893954917,774088023431472074
%N Bisection of A000081 (even part).
%H Alois P. Heinz, <a href="/A100034/b100034.txt">Table of n, a(n) for n = 0..400</a>
%p with(numtheory):
%p b:= proc(n) option remember; local d, j; `if`(n<2, n,
%p (add(add(d*b(d), d=divisors(j))*b(n-j), j=1..n-1))/(n-1))
%p end:
%p a:= n-> b(2*n):
%p seq(a(n), n=0..50); # _Alois P. Heinz_, May 16 2013
%t 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]; Table[a[n], {n, 0, 30}] (* _Jean-François Alcover_, Mar 19 2014, after _Alois P. Heinz_ *)
%Y Cf. A000081, A100427, A299098.
%K nonn,easy
%O 0,3
%A _N. J. A. Sloane_, Nov 20 2004
%E More terms from _Joshua Zucker_, May 12 2006
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