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A117437 Expansion of e.g.f.: exp(x)*sec(2*x). 2
1, 1, 5, 13, 105, 441, 5165, 30213, 469585, 3529201, 68525525, 629401213, 14664091065, 159175688361, 4326609913085, 54189700721013, 1683369010256545, 23894940183997921, 835066388382183845, 13248060325188261613 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Row sums of A117436.
Binomial transform of A002436 (with interpolated zeros).
LINKS
FORMULA
a(n) ~ n! * 2^(2*n+1) * (exp(Pi/4) + (-1)^n*exp(-Pi/4)) / Pi^(n+1). - Vaclav Kotesovec, Aug 04 2014
MATHEMATICA
With[{nn=30}, CoefficientList[Series[Exp[x]Sec[2x], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Dec 13 2011 *)
PROG
(Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!(Laplace( Exp(x)*Sec(2*x) ))); // G. C. Greubel, May 31 2021
(Sage) [factorial(n)*( exp(x)*sec(2*x) ).series(x, n+1).list()[n] for n in (0..30)] # G. C. Greubel, May 31 2021
(PARI) my(x='x+O('x^30)); Vec(serlaplace(exp(x)/cos(2*x))) \\ Michel Marcus, Jun 01 2021
CROSSREFS
Sequence in context: A304348 A305912 A180827 * A179089 A106046 A180362
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Mar 16 2006
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)