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A000911
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(2n+3)! /( n! * (n+1)! ).
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2
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6, 60, 420, 2520, 13860, 72072, 360360, 1750320, 8314020, 38798760, 178474296, 811246800, 3650610600, 16287339600, 72129646800, 317370445920, 1388495700900, 6044040109800, 26190840475800, 113034153632400
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| a(n)=6*A002802(n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 02 2007
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REFERENCES
| E. R. Hansen, A Table of Series and Products, Prentice-Hall, Englewood Cliffs, NJ, 1975, p. 99.
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FORMULA
| a(n)=A000984(n+1)*A000217(n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 10 2007
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MAPLE
| seq(binomial(2*n, n)*binomial(n, (n-2)), n=2..21); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 10 2007
with(combinat):a:=n->sum(sum(numbcomp(2*n, n), j=2..n), k=1..n): seq(a(n), n=2..21); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 10 2007
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PROG
| (PARI) a(n) = 2^(n+4)*polcoeff(pollegendre(n+4), n) (from R. Stephan)
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CROSSREFS
| Equals 2 * A051133(n+1). Cf. A001801.
Sequence in context: A006741 A120573 A028244 * A076100 A043033 A179711
Adjacent sequences: A000908 A000909 A000910 * A000912 A000913 A000914
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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