A089836 INVERT transform of A089835.

2, 28, 704, 26800, 1404416, 94890112, 7887853568, 779773444864, 89407927009280, 11666949886007296, 1707352344419336192, 276938622991133237248, 49316570352062326636544, 9565558797749164794511360, 2007400581177856844629016576, 453192947995950052758954115072

Offset: 1

Author

Antti Karttunen, Dec 05 2003

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..150

Programs

Maple

INVERT(A089835); INVERT([seq(A000108(n)*A000108(n)*(n+1)!,n=1..9)]);
a:= proc(n) option remember; local i; `if`(n<1, 1, add(a(n-i) *(2*i)!^2 /i!^3 /(i+1), i=1..n)) end: seq(a(n), n=1..20); # Alois P. Heinz, Apr 01 2009

Mathematica

a[n_] := a[n] = If[n < 1, 1, Sum[a[n - i] *(2 i)!^2 /i!^3 /(i + 1), {i, 1, n}]]; Array[a, 20] (* Jean-François Alcover, Mar 03 2016, adapted from Maple *)

Formula

a(n) ~ 16^n * n! / (Pi*n^2). - Vaclav Kotesovec, Sep 05 2014

Extensions

More terms from Alois P. Heinz, Apr 01 2009