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A002803
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a(n) = (2n+4)!/(4!*n!*(n+1)!).
(Formerly M4980 N2140)
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7
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1, 15, 140, 1050, 6930, 42042, 240240, 1312740, 6928350, 35565530, 178474296, 878850700, 4259045700, 20359174500, 96172862400, 449608131720, 2082743551350, 9569730173850, 43651400793000, 197809768856700
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OFFSET
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0,2
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REFERENCES
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C. Jordan, Calculus of Finite Differences. Budapest, 1939, p. 449.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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G.f.: 2F1(5/2,3;2;4x) =(1+x)/(1-4x)^(7/2). - R. J. Mathar, Aug 09 2015
D-finite with recurrence n*(n+1)*a(n) -2*(n+2)*(2*n+3)*a(n-1)=0. - R. J. Mathar, Feb 08 2021
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MATHEMATICA
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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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STATUS
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approved
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