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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A261056 Expansion of  ( 2-x^2 ) / (x^2+2*x-1)^2 . 1
2, 8, 27, 84, 248, 708, 1973, 5400, 14574, 38896, 102863, 269964, 703972, 1825612, 4711785, 12110064, 31010266, 79148184, 201420163, 511233156, 1294489296, 3270662036, 8247316765, 20758752648, 52163239622, 130875524096, 327893289783, 820410399804, 2050189683644 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

2nd column of A210637.

LINKS

Table of n, a(n) for n=0..28.

Index entries for linear recurrences with constant coefficients, signature (4,-2,-4,-1)

FORMULA

a(n) = 2*A006645(n+2) -A006645(n).

MATHEMATICA

CoefficientList[Series[(2-x^2)/(x^2+2*x-1)^2, {x, 0, 40}], x] (* or *) LinearRecurrence[{4, -2, -4, -1}, {2, 8, 27, 84}, 40] (* Harvey P. Dale, Feb 24 2017 *)

CROSSREFS

Cf. A210637.

Sequence in context: A100505 A102759 A292698 * A295135 A076884 A138388

Adjacent sequences:  A261053 A261054 A261055 * A261057 A261058 A261059

KEYWORD

nonn,easy

AUTHOR

R. J. Mathar, Aug 08 2015

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 27 01:16 EST 2021. Contains 349344 sequences. (Running on oeis4.)