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 A349889 a(n) = Sum_{k=0..n} (-1)^(n-k) * k^(2*n). 3
 1, 1, 15, 666, 59230, 8775075, 1948891581, 605698755508, 250914820143996, 133610836793706405, 88919025666286620475, 72317513878698256697166, 70571883548815735717843290, 81383769918571603591381635271 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA G.f.: Sum_{k>=0} (k^2 * x)^k/(1 + k^2 * x). a(n) ~ 1/(1 + exp(-2)) * n^(2*n). - Vaclav Kotesovec, Dec 10 2021 PROG (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*k^(2*n)); (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^2*x)^k/(1+k^2*x))) CROSSREFS Cf. A120485, A249459, A349884, A349891, A349902. Sequence in context: A280179 A223203 A279465 * A279531 A079600 A171113 Adjacent sequences:  A349886 A349887 A349888 * A349890 A349891 A349892 KEYWORD nonn AUTHOR Seiichi Manyama, Dec 04 2021 STATUS approved

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Last modified May 17 16:12 EDT 2022. Contains 353747 sequences. (Running on oeis4.)