login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A009128 Expansion of e.g.f. cosh(log(1+x))*cos(x). 1
1, 0, 0, -3, 7, -30, 194, -1365, 10893, -98028, 980324, -10783575, 129402835, -1682236842, 23551315878, -353269738185, 5652315810841, -96089368784280, 1729608638117192, -32862564124226667, 657251282484533151 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..250

FORMULA

a(n) ~ n! * (-1)^n * cos(1) / 2. - Vaclav Kotesovec, Jan 22 2015

MATHEMATICA

CoefficientList[Series[((1 + (1 + x)^2)*Cos[x])/(2*(1 + x)), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)

PROG

(PARI) x='x+O('x^30); Vec(serlaplace(cosh(log(1+x))*cos(x))) \\ G. C. Greubel, Jul 28 2018

(MAGMA) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cosh(Log(1+x))*Cos(x))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 28 2018

CROSSREFS

Sequence in context: A132105 A019021 A110505 * A053648 A138862 A080173

Adjacent sequences:  A009125 A009126 A009127 * A009129 A009130 A009131

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 26 01:22 EST 2020. Contains 338631 sequences. (Running on oeis4.)