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A061190
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a(n) = n^n - n.
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2
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1, 0, 2, 24, 252, 3120, 46650, 823536, 16777208, 387420480, 9999999990, 285311670600, 8916100448244, 302875106592240, 11112006825558002, 437893890380859360, 18446744073709551600, 827240261886336764160, 39346408075296537575406, 1978419655660313589123960
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listen;
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internal format)
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OFFSET
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0,3
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COMMENTS
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Number of endofunctions on [n] such that no element has a preimage of cardinality n. - Alois P. Heinz, Jul 21 2014
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LINKS
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FORMULA
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E.g.f.: 1/(1 + LambertW(-x)) - x*exp(x), where LambertW() is the Lambert W-function. - Ilya Gutkovskiy, Feb 08 2017
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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Lawrence H. Shirley (LShirley(AT)towson.edu), May 30 2001
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EXTENSIONS
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STATUS
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approved
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