OFFSET
0,3
FORMULA
E.g.f.: 1/cos(x)+ tan(x)/Q(0), where Q(k) = 4*k+1 -sin(x)/(2 + sin(x)/( 4*k+3 - sin(x)/(2 + sin(x)/Q(k+1) ))); (continued fraction). - Sergei N. Gladkovskii, Dec 08 2013
a(n) ~ n! * (exp(1) + exp(-1)*(-1)^n) / (Pi/2)^(n+1). - Vaclav Kotesovec, Jan 22 2015
MATHEMATICA
Exp[ Sin[ x ] ]/Cos[ x ]
CoefficientList[Series[E^Sin[x]*Sec[x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Extended and signs tested Mar 15 1997 by Olivier Gérard.
STATUS
approved