A275905 Expansion of (1-x-2*x^2) / (1-6*x+3*x^2-2*x^3).

1, 5, 25, 137, 757, 4181, 23089, 127505, 704125, 3888413, 21473113, 118581689, 654847621, 3616286885, 19970341825, 110282885537, 609018861517, 3363205196141, 18572740363369, 102564864314825, 566397375191125, 3127835138929013, 17272948436630353, 95386979953377329, 526758704688230941

Offset

0,2

Links

Colin Barker, Table of n, a(n) for n = 0..1000

T. Doslic, T. Short, Maximal matchings in polyspiro and benzenoid chains, arXiv:1511.00590, [math.CO], 2015. See Th. 3.4.

Index entries for linear recurrences with constant coefficients, signature (6,-3,2).

Formula

a(n) = 6*a(n-1)-3*a(n-2)+2*a(n-3) for n>2. - Colin Barker, Aug 26 2016

Mathematica

CoefficientList[Series[(1-x-2x^2)/(1-6x+3x^2-2x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{6, -3, 2}, {1, 5, 25}, 40] (* Harvey P. Dale, May 14 2019 *)

Prog

(PARI) Vec((1-x-2*x^2)/(1-6*x+3*x^2-2*x^3) + O(x^30)) \\ Colin Barker, Aug 26 2016

Crossrefs

Sequence in context: A366431 A048370 A272706 * A124891 A358504 A365772

Adjacent sequences: A275902 A275903 A275904 * A275906 A275907 A275908

Keyword

nonn,easy

Author

N. J. A. Sloane, Aug 25 2016

Status

approved