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A100262
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Expansion of A(x)^2, where A(x) = o.g.f. of n^n (A000312).
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0
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1, 2, 9, 62, 582, 6978, 102339, 1779222, 35809052, 819103178, 20987183525, 595341928814, 18519658804818, 626784970780690, 22926284614808071, 901188628763393606, 37882728189752349304, 1695744102631158083866
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Thomas Wieder, The number of certain k-combinations of an n-set, Applied Mathematics Electronic Notes, vol. 8 (2008).
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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]
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EXAMPLE
| (1 + x + 4x^2 + 27x^3 + 256x^4 +...)^2 = 1 + 2x + 9x^2 + 62x^3 +...
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CROSSREFS
| Sequence in context: A173498 A113662 A052820 * A166886 A003577 A085928
Adjacent sequences: A100259 A100260 A100261 * A100263 A100264 A100265
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KEYWORD
| nonn
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AUTHOR
| Ralf Stephan, Nov 20 2004
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