cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Aug 08 2015

Keywords

Comments

2nd column of A210637.

Crossrefs

Cf. A210637.

Programs

  • 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 *)

Formula

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