A136636 a(n) = n * C(2*3^(n-1), n) for n>=1.

2, 30, 2448, 1265004, 4368213360, 106458751541142, 19173684851378353296, 26413015283743616538733008, 285290979402099025600644272168880, 24601033850235942230699563821233785600080

Offset: 1

Author

Vladeta Jovovic and Paul D. Hanna, Jan 15 2008

Keywords

• nonn
• easy

Comments

Equals column 1 of triangle A136635.

Crossrefs

Cf. A136635 (triangle), A014070 (main diagonal), A136393 (column 0), A136637 (row sums), A136638 (antidiagonal sums).

Programs

Maple

A136636:=n->n*binomial(2*3^(n-1), n); seq(A136636(n), n=1..10); # Wesley Ivan Hurt, Apr 29 2014

Mathematica

Table[n*Binomial[2*3^(n - 1), n], {n, 10}] (* Wesley Ivan Hurt, Apr 29 2014 *)

PARI

{a(n)=n*binomial(2*3^(n-1),n)}

Formula

a(n) ~ 2^n * 3^(n*(n-1)) / (n-1)!. - Vaclav Kotesovec, Jul 02 2016