A218142 a(n) = Stirling2(n^2+n, n).

1, 1, 31, 86526, 45232115901, 7713000216608565075, 666480349285726891499539272955, 41929298560838945526242744414099901692285884, 2610516895723221966171633379256064857587637240616032299710417

Offset

0,3

Links

Paul D. Hanna, Table of n, a(n) for n = 0..25

Formula

a(n) = [x^n] Sum_{k>=0} k^((n+1)*k) * exp(-k^(n+1)*x) * x^k / k!.

a(n) = [x^(n^2)] 1 / Product_{k=1..n} (1-k*x).

a(n) ~ n^(n^2+n)/n!. - Vaclav Kotesovec, May 11 2014

Example

O.g.f.: A(x) = 1 + x + 31*x^2 + 86526*x^3 + 45232115901*x^4 +...

Mathematica

Table[StirlingS2[n^2+n, n], {n, 0, 10}] (* Vaclav Kotesovec, May 11 2014 *)

Prog

(PARI) {a(n)=polcoeff(sum(k=0, n, (k^(n+1))^k*exp(-k^(n+1)*x +x*O(x^n))*x^k/k!), n)}
(PARI) {a(n)=polcoeff(1/prod(k=1, n, 1-k*x +x*O(x^(n^2))), n^2)}
(PARI) {Stirling2(n, k)=n!*polcoeff(((exp(x+x*O(x^n))-1)^k)/k!, n)}
{a(n) = Stirling2(n^2+n, n)}
for(n=0, 10, print1(a(n), ", "))
(Maxima) makelist(stirling2(n^2+n, n), n, 0, 30 ); /* Martin Ettl, Oct 21 2012 */

Crossrefs

Cf. A008277, A218141, A218143, A007820, A217913, A217914, A217915.

Sequence in context: A033176 A263163 A188956 * A117579 A249584 A351135

Adjacent sequences: A218139 A218140 A218141 * A218143 A218144 A218145

Keyword

nonn

Author

Paul D. Hanna, Oct 21 2012

Status

approved