OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..300
FORMULA
a(n) = sum(L(k)L(n-k),k=0..n), where L(n) is a central Lah number.
a(n) ~ n! * 16^n / (Pi*n). - Vaclav Kotesovec, Oct 06 2019
MAPLE
a := n -> if n=0 then 1 else binomial(2*n-1, n-1)*(2*n)!/n! fi;
seq(sum(a(k)*a(n-k), k=0..n), n=0..12);
MATHEMATICA
a[n_] := If[n == 0, 1, Binomial[2n - 1, n - 1](2n)!/n!]
Table[Sum[a[k]a[n - k], {k, 0, n}], {n, 0, 20}]
PROG
(Maxima) a(n) := if n=0 then 1 else binomial(2*n-1, n-1)*(2*n)!/n!;
makelist(sum(a(k)*a(n-k), k, 0, n), n, 0, 12);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emanuele Munarini, Mar 11 2011
STATUS
approved