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A275906 Expansion of (1+x+x^2) / (1-4*x-4*x^2-x^3). 1
1, 5, 25, 121, 589, 2865, 13937, 67797, 329801, 1604329, 7804317, 37964385, 184679137, 898378405, 4370194553, 21258970969, 103415040493, 503066240401, 2447184094545, 11904416380277, 57909468139689, 281702722174409, 1370353177636669, 6666133067384001, 32427647702257089, 157745476256201029 (list; graph; refs; listen; history; text; internal format)
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 (4,4,1).

FORMULA

a(n) = 4*a(n-1)+4*a(n-2)+a(n-3). - Colin Barker, Aug 26 2016

PROG

(PARI) Vec((1+x+x^2)/(1-4*x-4*x^2-x^3) + O(x^40)) \\ Colin Barker, Aug 26 2016

CROSSREFS

Sequence in context: A268453 A218989 A078717 * A249454 A250347 A278282

Adjacent sequences:  A275903 A275904 A275905 * A275907 A275908 A275909

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Aug 25 2016

STATUS

approved

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Last modified March 18 13:47 EDT 2019. Contains 321289 sequences. (Running on oeis4.)