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A037960
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(n+2)!*n*(3*n+1)/24.
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4
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0, 1, 14, 150, 1560, 16800, 191520, 2328480, 30240000, 419126400, 6187104000, 97037740800, 1612798387200, 28332944640000, 524813313024000, 10226013557760000, 209144207720448000, 4480594531725312000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| For n>=1, a(n) is equal to the number of surjections from {1,2,..,n+2} onto {1,2,...,n}. - Aleksandar M. Janjic and Milan R. Janjic (agnus(AT)blic.net), Feb 24 2007
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REFERENCES
| The right-hand side of a binomial coefficient identity in H. W. Gould, Combinatorial Identities, Morgantown, 1972.
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LINKS
| Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
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PROG
| (PARI) n*(3*n+1)*(n+2)!/24 \\ Charles R Greathouse IV, Nov 02 2011
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CROSSREFS
| Cf. A019538, A001286.
Sequence in context: A009802 A153598 A180347 * A016163 A153884 A154239
Adjacent sequences: A037957 A037958 A037959 * A037961 A037962 A037963
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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