A092470 a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (n+2*i)!/((2*i)! * j! * k!).

1, 3, 42, 774, 19440, 605520, 22856400, 1012258800, 51590125440, 2974547691360, 191478611348640, 13613255894921760, 1059445820574741600, 89583977589282015840, 8178390058456647469440, 801733426581997672963200

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..200

Formula

a(n) ~ c * (27/4)^n * n^n / exp(n), where c = 2.22899138292196283171077335844... - Vaclav Kotesovec, Oct 30 2021

Prog

(PARI) a(n)=sum(i=0, n, sum(j=0, i, sum(k=0, j, if(i+j+k-n, 0, (n+2*i)!/(2*i)!/j!/k!))))

Crossrefs

Sequence in context: A219619 A097068 A269046 * A355796 A336572 A366006

Adjacent sequences: A092467 A092468 A092469 * A092471 A092472 A092473

Keyword

nonn

Author

Benoit Cloitre, Mar 25 2004

Status

approved