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

0,2

LINKS

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), n=0,1,2,... [From Tilman Neumann (Tilman.Neumann(AT)web.de), Dec 13 2008]

EXAMPLE

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

CROSSREFS

Sequence in context: A146887 A113662 A052820 this_sequence A003577 A085928 A130169

Adjacent sequences: A100259 A100260 A100261 this_sequence A100263 A100264 A100265

KEYWORD

nonn

AUTHOR

Ralf Stephan, Nov 20 2004

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Last modified December 11 12:57 EST 2009. Contains 170656 sequences.


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