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A275903 Expansion of (1+4*x^2) / (1-5*x+4*x^2-4*x^3). 1
1, 5, 25, 109, 465, 1989, 8521, 36509, 156417, 670133, 2871033, 12300301, 52697905, 225772453, 967271849, 4144061053, 17754307681, 76064381589, 325880921433, 1396164311533, 5981555398289, 25626643431045, 109791652808201, 470377911909981, 2015229522041281, 8633802573799285 (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 (5,-4,4).

FORMULA

a(n) = 5*a(n-1)-4*a(n-2)+4*a(n-3) for n>2. - Colin Barker, Aug 26 2016

PROG

(PARI) Vec((1+4*x^2)/(1-5*x+4*x^2-4*x^3) + O(x^40)) \\ Colin Barker, Aug 26 2016

CROSSREFS

Sequence in context: A074419 A247105 A272249 * A273828 A147161 A282077

Adjacent sequences:  A275900 A275901 A275902 * A275904 A275905 A275906

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Aug 25 2016

STATUS

approved

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Last modified September 18 01:00 EDT 2021. Contains 347497 sequences. (Running on oeis4.)