login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A159039 E.g.f. sec(x)/(1-x) = 1/( cos(x) * (1-x) ). 0
1, 1, 3, 9, 41, 205, 1291, 9037, 73681, 663129, 6681811, 73499921, 884701817, 11501123621, 161215091675, 2418226375125, 38711013514145, 658087229740465, 11847975015003811, 225111525285072409, 4502600876889685705, 94554618414683399805, 2080270953997427933611 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
E.g.f.: sec(x)/(1-x) = 1/U(0) where U(k)= 1 - x/(1 - x/(x + (2*k+1)*(2*k+2)/U(k+1)) ; (continued fraction, 3-step). - Sergei N. Gladkovskii, Oct 17 2012
E.g.f.: (1-1/Q(0))/(1-x), where Q(k)= 1 - (2*k+1)*(2*k+2)/x^2 + 1/x^2*(2*k+1)*(2*k+2)/Q(k+1); (continued fraction). - Sergei N. Gladkovskii, May 01 2013
a(n) ~ n!/cos(1). - Vaclav Kotesovec, Jun 27 2013
MAPLE
G(x):=sec(x)/(1-x): f[0]:=G(x): for n from 1 to 21 do f[n]:=diff(f[n-1], x) od: x:=0: seq(f[n], n=0..21); #
MATHEMATICA
CoefficientList[Series[1/(Cos[x]*(1-x)), {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Jun 27 2013 *)
PROG
(PARI) x='x+O('x^66); Vec(serlaplace(1/(cos(x)*(1-x)))) \\ Joerg Arndt, May 01 2013
CROSSREFS
Sequence in context: A274739 A012246 A012099 * A074502 A109743 A139150
KEYWORD
nonn
AUTHOR
Zerinvary Lajos, Apr 03 2009
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)