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 A034908 One half of octo-factorial numbers. 11
 1, 10, 180, 4680, 159120, 6683040, 334152000, 19380816000, 1279133856000, 94655905344000, 7761784238208000, 698560581438720000, 68458936980994560000, 7256647319985423360000, 827257794478338263040000, 100925450926357268090880000, 13120308620426444851814400000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Table of n, a(n) for n = 1..333 FORMULA 2*a(n) = (8*n-6)(!^8) := product(8*j-6, j=1..n) = 2^n*A007696(n), A007696(n)=(4*n-3)(!^4) := product(4*j-3, j=1..n). E.g.f.: (-1+(1-8*x)^(-1/4))/2. G.f.: x/(1-10x/(1-8x/(1-18x/(1-16x/(1-26x/(1-24x/(1-34x/(1-32x/(1-... (continued fraction). - Philippe Deléham, Jan 07 2012 MATHEMATICA Drop[With[{nn = 40}, CoefficientList[Series[(-1 + (1 - 8*x)^(-1/4))/2, {x, 0, nn}], x]*Range[0, nn]!], 1] (* G. C. Greubel, Feb 26 2018 *) PROG (PARI) x='x+O('x^30); Vec(serlaplace((-1+(1-8*x)^(-1/4))/2)) \\ G. C. Greubel, Feb 26 2018 (MAGMA) [(&*[(8*k-6): k in [1..n]])/2: n in [1..30]]; // G. C. Greubel, Feb 26 2018 CROSSREFS Cf. A045755, A034909, A039410, A039411, A039412. Sequence in context: A067416 A113671 A001762 * A030048 A318796 A054918 Adjacent sequences:  A034905 A034906 A034907 * A034909 A034910 A034911 KEYWORD easy,nonn AUTHOR EXTENSIONS Terms a(16) onward added by G. C. Greubel, Feb 26 2018 STATUS approved

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Last modified January 19 20:41 EST 2020. Contains 331066 sequences. (Running on oeis4.)