

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
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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



