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 A011266 a(n) = 2^(n*(n-1)/2)*n!. 14
 1, 1, 4, 48, 1536, 122880, 23592960, 10569646080, 10823317585920, 24936923717959680, 127677049435953561600, 1438154284846580917862400, 35344079704389572637386342400, 1882001556099335963795547960115200, 215842994465920643015783804449692057600 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Let A = the sum of the n-th powers of the first 2^{n-1} terms of A001969, and similarly let B = the sum of the n-th powers of the first 2^{n-1} terms of A000069. Then a(n) = |A-B|. - Jeffrey Shallit, Nov 29 2019 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..77 Richard P. Stanley, Acyclic Orientations of Graphs, Discrete Mathematics, 5 (1973), pages 171-178, doi:10.1016/0012-365X(73)90108-8. FORMULA From Mehdi Naima, Mar 09 2022: (Start) a(n) = a(n-1)*n*2^(n-1), a(0) = 1. G.f. satisfies A(x) = 1 + x * (x * A(2*x))'. (End) MAPLE a:= n-> 2^(n*(n-1)/2)*n!: seq(a(n), n=0..15); # Alois P. Heinz, Apr 21 2020 MATHEMATICA Table[2^((n(n-1))/2) n!, {n, 0, 20}] (* Harvey P. Dale, Dec 16 2012 *) PROG (PARI) a(n) = n! << binomial(n, 2); \\ Kevin Ryde, Mar 10 2022 CROSSREFS Main diagonal of A046860. Cf. A000069, A001969. Sequence in context: A353922 A332865 A346949 * A360820 A362828 A197927 Adjacent sequences: A011263 A011264 A011265 * A011267 A011268 A011269 KEYWORD nonn AUTHOR N. J. A. Sloane STATUS approved

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Last modified August 8 12:12 EDT 2024. Contains 375021 sequences. (Running on oeis4.)