A228554 x-values in the solution to the Pell equation x^2 - 85*y^2 = -1.

378, 216041742, 123476065138818, 70571263317093720342, 40334158693601634671687178, 23052504391353119813669652619422, 13175382254784845233371524284127523858, 7530231623112168370599341126488007078134182

Offset

1,1

Comments

All terms are multiples of 378.

Links

Colin Barker, Table of n, a(n) for n = 1..150

Index entries for linear recurrences with constant coefficients, signature (571538,-1).

Formula

a(n) = 571538*a(n-1)-a(n-2).

G.f.: 378*x*(x+1) / (x^2-571538*x+1).

Mathematica

LinearRecurrence[{571538, -1}, {378, 216041742}, 20] (* Harvey P. Dale, Jul 10 2019 *)

Prog

(PARI) Vec(378*x*(x+1)/(x^2-571538*x+1) + O(x^30))

Crossrefs

Cf. A228555 gives the corresponding y-values.

Sequence in context: A171115 A328552 A225994 * A108385 A341188 A020369

Adjacent sequences: A228551 A228552 A228553 * A228555 A228556 A228557

Keyword

nonn,easy

Author

Colin Barker, Aug 25 2013

Status

approved