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 A306280 a(n) = Sum_{k=0..n} binomial(n,k)*binomial(n^2+k,k). 1
 1, 3, 26, 416, 9708, 297662, 11306572, 512307336, 26968496504, 1617489748394, 108885682104744, 8129721925098468, 666736347200187804, 59582961423951290184, 5762936296492591067968, 599807329803134064385488, 66843498592187788579795440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..337 FORMULA From Vaclav Kotesovec, Feb 08 2019: (Start) a(n) ~ exp(1) * A135860(n). a(n) ~ exp(n + 3/2) * n^(n - 1/2) / sqrt(2*Pi). (End) MATHEMATICA a[n_] := Sum[Binomial[n, k] * Binomial[n^2+k, k], {k, 0, n}]; Array[a, 20, 0] (* Amiram Eldar, Feb 03 2019 *) PROG (PARI) {a(n) = sum(k=0, n, binomial(n, k)*binomial(n^2+k, k))} CROSSREFS Cf. A001850, A114496, A135860, A156886, A156887. Sequence in context: A326431 A206403 A192554 * A305144 A206402 A300954 Adjacent sequences: A306277 A306278 A306279 * A306281 A306282 A306283 KEYWORD nonn AUTHOR Seiichi Manyama, Feb 02 2019 STATUS approved

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Last modified March 22 09:08 EDT 2023. Contains 361423 sequences. (Running on oeis4.)