A261056 Expansion of ( 2-x^2 ) / (x^2+2*x-1)^2 .

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

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