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A037961
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(n+3)!*n^2*(n+1)/48.
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2
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0, 1, 30, 540, 8400, 126000, 1905120, 29635200, 479001600, 8083152000, 142702560000, 2637143308800, 50999300352000, 1031319184896000, 21785854970880000, 480178027929600000, 11029155770400768000
(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+3} 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
| Vincenzo Librandi, Table of n, a(n) for n = 0..400
Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
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PROG
| (PARI) a(n)=(n+3)!*n^2*(n+1)/48 \\ Charles R Greathouse IV, Nov 02 2011
(MAGMA) [Factorial(n+3)*n^2*(n+1)/48: n in [0..20]]; // Vincenzo Librandi, Nov 18 2011
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CROSSREFS
| Cf. A001286, A037960.
Sequence in context: A050982 A004327 A139626 * A143399 A075510 A028200
Adjacent sequences: A037958 A037959 A037960 * A037962 A037963 A037964
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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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