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A157765 Expansion of (2 - 2*x) / (1 - 10*x - 7*x^2). 1
2, 18, 194, 2066, 22018, 234642, 2500546, 26647954, 283983362, 3026369298, 32251576514, 343700350226, 3662764537858, 39033547830162, 415974830066626, 4432983135477394, 47241655165240322, 503447433600744978, 5365165922164132034, 57175791256846535186 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Colin Barker, Table of n, a(n) for n = 0..900

Tomislav Došlić and Frode Måløy, Chain hexagonal cacti: Matchings and independent sets, Discr. Math., 310 (2010), 1676-1690.

Index entries for linear recurrences with constant coefficients, signature (10, 7).

FORMULA

From Colin Barker, Nov 25 2017: (Start)

a(n) = ((5-4*sqrt(2))^n*(-1+sqrt(2)) + (1+sqrt(2))*(5+4*sqrt(2))^n) / sqrt(2).

a(n) = 10*a(n-1) + 7*a(n-2) for n > 1.

(End)

PROG

(PARI) Vec(2*(1 - x) / (1 - 10*x - 7*x^2) + O(x^40)) \\ Colin Barker, Nov 25 2017

CROSSREFS

Sequence in context: A066274 A052623 A155542 * A156341 A262718 A210989

Adjacent sequences:  A157762 A157763 A157764 * A157766 A157767 A157768

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 22 2010

STATUS

approved

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Last modified October 18 11:56 EDT 2018. Contains 316321 sequences. (Running on oeis4.)