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A024348 Expansion of tan(x^2). 2
2, 240, 483840, 4704860160, 140016638361600, 9962283186074419200, 1448674564423160954880000, 386164234578290422390456320000, 174195452900540085852580211589120000 (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

Tan[ x^2 ] (* [ x^(4n+2) ] *)

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 May 31 08:09 EDT 2020. Contains 334747 sequences. (Running on oeis4.)