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A009667 E.g.f.  tan(sin(x))*x, even numbered terms only. 2
0, 2, 4, -18, -856, -10950, 502764, 42386918, 552455120, -212988964878, -23803145936300, 497029073217886, 554580759766596984, 68481112266792124458, -10157252026016020122820 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Robert Israel, Table of n, a(n) for n = 0..250

FORMULA

a(n) = 2*A024225(n). [Martin Ettl, Nov 08 2012]

a(n) = (2*n)!*[x^(2*n)] tan(sin(x))*x. - Robert Israel, Mar 11 2019

MAPLE

S:= series(x*tan(sin(x)), x, 61):

seq(n!*coeff(S, x, n), n=0..60, 2); # Robert Israel, Mar 11 2019

MATHEMATICA

nn = 30; t = Range[0, nn]! CoefficientList[Series[Tan[Sin[x]]*x, {x, 0, nn}], x]; Take[t, {1, nn, 2}] (* T. D. Noe, Nov 08 2012 *)

CROSSREFS

Cf. A024225.

Sequence in context: A306193 A323702 A318531 * A009508 A275000 A290595

Adjacent sequences:  A009664 A009665 A009666 * A009668 A009669 A009670

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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Last modified December 6 06:14 EST 2021. Contains 349563 sequences. (Running on oeis4.)