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A100262 Expansion of A(x)^2, where A(x) = o.g.f. of n^n (A000312). 0
1, 2, 9, 62, 582, 6978, 102339, 1779222, 35809052, 819103178, 20987183525, 595341928814, 18519658804818, 626784970780690, 22926284614808071, 901188628763393606, 37882728189752349304, 1695744102631158083866 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..17.

Thomas Wieder, The number of certain k-combinations of an n-set, Applied Mathematics Electronic Notes, vol. 8 (2008).

FORMULA

a(n) = Sum_{k=0..n} k^k * (n-k)^(n-k). - Tilman Neumann, Dec 13 2008

EXAMPLE

(1 + x + 4x^2 + 27x^3 + 256x^4 +...)^2 = 1 + 2x + 9x^2 + 62x^3 +...

MATHEMATICA

nn=17; f[x_]=1+Sum[n^n x^n, {n, 1, nn}]; CoefficientList[Series[f[x]^2, {x, 0, nn}], x] (* Geoffrey Critzer, Nov 05 2013 *)

CROSSREFS

Cf. A053729.

Sequence in context: A113662 A052820 A213528 * A166886 A212413 A003577

Adjacent sequences:  A100259 A100260 A100261 * A100263 A100264 A100265

KEYWORD

nonn

AUTHOR

Ralf Stephan, Nov 20 2004

STATUS

approved

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Last modified August 20 02:10 EDT 2019. Contains 326136 sequences. (Running on oeis4.)