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 A098274 Sum[k=0..n, C(n,k)^2*C(n+k,n)*C(n+2k,n)]. 1
 1, 7, 163, 5191, 191251, 7665757, 324610399, 14287393351, 647133545107, 29966682138757, 1412267381766913, 67516263948005341, 3266295503353540399, 159606073670867165713, 7866072852462175900663 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Coefficients in a simultaneous approximation to zeta(2) and zeta(3). LINKS W. Zudilin, Approximations to -, di and trilogarithms FORMULA a(n) = (-1)^n * Sum[k=0..n, (-1)^k*C(n, k)*C(n+k, k)^3]. MATHEMATICA Table[Sum[Binomial[n, k]^2 Binomial[n+k, n]Binomial[n+2k, n], {k, 0, n}], {n, 0, 20}] (* Harvey P. Dale, Aug 17 2019 *) CROSSREFS Cf. A005258, A098275. Sequence in context: A201179 A218998 A220921 * A027549 A212856 A169608 Adjacent sequences:  A098271 A098272 A098273 * A098275 A098276 A098277 KEYWORD nonn,easy,changed AUTHOR Ralf Stephan, Sep 03 2004 STATUS approved

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Last modified August 19 20:20 EDT 2019. Contains 326133 sequences. (Running on oeis4.)