OFFSET
0,5
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..400
Vaclav Kotesovec, Graph - abs(e.g.f.) in the complex plane
FORMULA
a(n) ~ n! / (sqrt(2*Pi) * (exp(sqrt(Pi/2))-1) * (exp(-sqrt(Pi/2))-1)^n). - Vaclav Kotesovec, Feb 08 2015
EXAMPLE
E.g.f. = 1 + 12*x^4/4! - 120*x^5/5! + 1020*x^6/6! + ...
MAPLE
seq(coeff(series(factorial(n)*sec(log(x+1)*log(x+1)), x, n+1), x, n), n = 0 .. 20); # Muniru A Asiru, Oct 28 2018
MATHEMATICA
With[{nn=20}, CoefficientList[Series[Sec[Log[x+1]^2], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Sep 13 2014 *)
PROG
(PARI) x='x+O('x^30); Vec(serlaplace(1/cos(log(x+1)^2))) \\ G. C. Greubel, Oct 28 2018
(Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( 1/Cos(Log(x+1)^2) )); [Factorial(n-1)*b[n]: n in [1..m-1]]; // G. C. Greubel, Oct 28 2018
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Definition clarified by Harvey P. Dale, Sep 13 2014
STATUS
approved