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Search: id:A001879
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| A001879 |
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(2n+2)!/(n!2^(n+1)).
(Formerly M4251 N1775)
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+0
4
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| 1, 6, 45, 420, 4725, 62370, 945945, 16216200, 310134825, 6547290750, 151242416325, 3794809718700, 102776096548125, 2988412653476250, 92854250304440625, 3070380543400170000, 107655217802968460625, 3989575718580595893750, 155815096120119939628125
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77 (Problem 10, values of Bessel polynomials).
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FORMULA
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E.g.f.: (1+x)/(1-2x)^(5/2).
a(n)n=a(n-1)(2n+1)(n+1); a(n)=a(n-1)(2n+4)-a(n-2)(2n-1), if n>0. - Michael Somos Feb 25 2004
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PROGRAM
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(PARI) a(n)=if(n<0, 0, (2*n+2)!/n!/2^(n+1))
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CROSSREFS
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Cf. A002544, A001814, A001876-A001878.
Second column of triangle A001497. Equals [A001147(n+1)-A001147(n)]/2.
Sequence in context: A101600 A135148 A137974 this_sequence A019577 A097814 A084064
Adjacent sequences: A001876 A001877 A001878 this_sequence A001880 A001881 A001882
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KEYWORD
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nonn,easy
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AUTHOR
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njas
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EXTENSIONS
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Entry revised Aug 31 2004 (thanks to Ralf Stephan and Michael Somos).
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