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 A009569 Expansion of e.g.f. sinh(log(1+tan(x))). 2
 0, 1, -1, 5, -20, 136, -976, 8840, -88640, 1019776, -12933376, 181318400, -2767631360, 45821372416, -816582578176, 15596531778560, -317710534983680, 6876972491309056, -157606194409701376, 3812752893951672320, -97090584769337753600, 2596013487025352605696 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS G. C. Greubel, Table of n, a(n) for n = 0..430 FORMULA a(n) ~ n! * (-1)^(n+1) * 4^n / Pi^(n+1). - Vaclav Kotesovec, Jan 23 2015 MATHEMATICA CoefficientList[Series[(Tan[x]*(2 + Tan[x]))/(2*(1 + Tan[x])), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *) With[{nmax = 50}, CoefficientList[Series[Sinh[Log[1 + Tan[x]]], {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, Jan 21 2018 *) PROG (PARI) x='x+O('x^30); concat([0], Vec(serlaplace(sinh(log(1+tan(x)))))) \\ G. C. Greubel, Jan 21 2018 CROSSREFS Sequence in context: A081067 A318250 A024066 * A061964 A133667 A318433 Adjacent sequences:  A009566 A009567 A009568 * A009570 A009571 A009572 KEYWORD sign,easy AUTHOR EXTENSIONS Extended with signs by Olivier Gérard, Mar 15 1997 Terms a(20) and a(21) added by G. C. Greubel, Jan 21 2018 STATUS approved

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Last modified January 19 19:49 EST 2019. Contains 319309 sequences. (Running on oeis4.)