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A107869
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Column 1 of triangle A107867; a(n) = binomial( n*(n+1)/2 + n+1, n).
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1
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1, 3, 15, 120, 1365, 20349, 376740, 8347680, 215553195, 6358402050, 210980549208, 7778680504140, 315502265971620, 13961746143269400, 669413654240461560, 34569147570568156800, 1912924003884628655655, 112923282067713332728110
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OFFSET
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0,2
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LINKS
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PROG
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(PARI) a(n)=binomial(n*(n+1)/2+n+1, n)
(Sage) [binomial(binomial(binomial(n+1, n), n-1), n-1) for n in range(1, 19)] # Zerinvary Lajos, Nov 30 2009
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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