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A228206 y-values in the solution to x^2 - 13y^2 = 108. 2
1, 3, 6, 11, 22, 39, 69, 122, 241, 426, 753, 1331, 2629, 4647, 8214, 14519, 28678, 50691, 89601, 158378, 312829, 552954, 977397, 1727639, 3412441, 6031803, 10661766, 18845651, 37224022, 65796879, 116302029, 205574522, 406051801, 717733866, 1268660553 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This equation is used for worked examples in the Robertson link.

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

John P. Robertson, Solving the generalized Pell equation x^2 - Dy^2 = N

Index entries for linear recurrences with constant coefficients, signature (0,0,0,11,0,0,0,-1).

FORMULA

G.f.: x*(x+1)*(x^6+2*x^5+4*x^4+7*x^3+4*x^2+2*x+1) / ((x^4-3*x^2-1)*(x^4+3*x^2-1)).

a(n) = 11*a(n-4)-a(n-8).

PROG

(PARI) Vec(x*(x+1)*(x^6+2*x^5+4*x^4+7*x^3+4*x^2+2*x+1)/((x^4-3*x^2-1)*(x^4+3*x^2-1)) + O(x^100))

CROSSREFS

Cf. A228205

Sequence in context: A191581 A192896 A115030 * A195734 A018177 A103322

Adjacent sequences:  A228203 A228204 A228205 * A228207 A228208 A228209

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Aug 16 2013

STATUS

approved

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Last modified July 26 08:42 EDT 2021. Contains 346294 sequences. (Running on oeis4.)