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 A024348 Expansion of tan(x^2). 2
 2, 240, 483840, 4704860160, 140016638361600, 9962283186074419200, 1448674564423160954880000, 386164234578290422390456320000, 174195452900540085852580211589120000, 125069935244132704803738682551120691200000, 136166701199201243586499061842886142826905600000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Robert Israel, Table of n, a(n) for n = 0..116 FORMULA a(n) = A000182(n)*A001813(2*n+1). - Robert Israel, Dec 20 2018 a(n) = 2 * A009767(n). - Sean A. Irvine, Jul 01 2019 MAPLE S:= series(tan(x), x, 52): seq(coeff(S, x, 2*k+1)*(4*k+2)!, k=0..25); # Robert Israel, Dec 20 2018 MATHEMATICA With[{m=50}, CoefficientList[Series[Tan[x^2], {x, 0, m}], x]*Range[0, m]!][[3;; ;; 4]] (* G. C. Greubel, Jan 31 2022 *) PROG (Sage) [factorial(4*n+2)*( tan(x^2) ).series(x, 4*n+3).list()[4*n+2] for n in (0..20)] # G. C. Greubel, Jan 31 2022 (Magma) m:=50; R:=PowerSeriesRing(Rationals(), m); b:= Coefficients(R!(Laplace( Tan(x^2) ))); [b[4*n-3]: n in [1..Floor((m-2)/4)]]; // G. C. Greubel, Jan 31 2022 CROSSREFS Cf. A000182, A001813. Sequence in context: A087226 A217972 A071967 * A006523 A294319 A055968 Adjacent sequences: A024345 A024346 A024347 * A024349 A024350 A024351 KEYWORD nonn AUTHOR R. H. Hardin EXTENSIONS Extended and signs tested by Olivier Gérard, Mar 15 1997 STATUS approved

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Last modified September 16 17:19 EDT 2024. Contains 375976 sequences. (Running on oeis4.)