OFFSET
0,4
COMMENTS
Note that a(27) is negative. - Vaclav Kotesovec, Jan 24 2015
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..200
FORMULA
a(n) ~ n! * (-1)^n / (GAMMA(-1/cos(1)) * n^(1+1/cos(1))) * (1 - sin(1)*log(n)/((cos(1))^2*n)*(1+1/cos(1))). - Vaclav Kotesovec, Jan 24 2015
MATHEMATICA
Exp[ Log[ 1+x ]/Cos[ x ] ]
CoefficientList[Series[(1 + x)^Sec[x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)
PROG
(PARI) seq(n)={my(x='x+O('x^n)); Vec(serlaplace(exp(log(1+x)/cos(x))))} \\ Andrew Howroyd, Feb 25 2018
CROSSREFS
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
a(22)-a(23) from Andrew Howroyd, Feb 25 2018
STATUS
approved