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A087413
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Sum(k=1, n, C(3*k,k))/3.
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0
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1, 6, 34, 199, 1200, 7388, 46148, 291305, 1853580, 11868585, 76380825, 493606725, 3201081873, 20821158233, 135776966761, 887393271310, 5811082966885, 38119865826420, 250447855600320, 1647729357535485, 10854207824989830
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| G.f.: 1/((3*g-1)*(g^3-2*g^2+g-1)*(g-1)^2) where g*(1-g)^2 = x - Mark van Hoeij, Nov 10 2011
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PROG
| (PARI) a(n)=sum(k=1, n, binomial(3*k, k))/3 \\ Charles R Greathouse IV, Nov 10 2011
(PARI) a=vector(99, i, 1); for(n=2, #a, a[n]=a[n-1]+binomial(3*n, n)/3); a \\ Charles R Greathouse IV, Nov 10 2011
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CROSSREFS
| Sequence in context: A049608 A154244 A126501 * A059228 A079568 A063090
Adjacent sequences: A087410 A087411 A087412 * A087414 A087415 A087416
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 21 2003
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