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1, 6, 35, 210, 1287, 8008, 50388, 319770, 2042975, 13123110, 84672315, 548354040, 3562467300, 23206929840, 151532656696, 991493848554, 6499270398159, 42671977361650, 280576272201225
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..18.
Milan Janjic, Two Enumerative Functions
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FORMULA
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G.f.: (2*(-1+Hypergeometric2F1[-(1/3),1/3,-(1/2),(27*x)/4]))/(3*x) [From Harvey P. Dale
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EXAMPLE
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if n=0 then C(3*0+1,0+1)= C(1,1)=1
if n=10 then C(3*10+1,10+1)= C(31,11)=84672315
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MATHEMATICA
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Table[Binomial[3n+1, n+1], {n, 0, 20}] (* From Harvey P. Dale, Jul 19 2011 *)
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CROSSREFS
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Sequence in context: A001109 A180033 A144638 * A213452 A000399 A081051
Adjacent sequences: A117668 A117669 A117670 * A117672 A117673 A117674
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KEYWORD
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easy,nonn
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AUTHOR
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Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 12 2006
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STATUS
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approved
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