A228547 y-values in the solution to the Pell equation x^2 - 74*y^2 = -1.

5, 36985, 273615025, 2024203917965, 14975060311490045, 110785494160199434945, 819591070822095108233065, 6063334631156365450508779925, 44856548781703720780768845652085, 331848741823709495179762469625344905

Offset

1,1

Comments

All terms are multiples of 5.

Links

Colin Barker, Table of n, a(n) for n = 1..250

Christian Aebi and Grant Cairns, Lattice equable quadrilaterals III: tangential and extangential cases, Integers (2023) Vol. 23, #A48.

Index entries for linear recurrences with constant coefficients, signature (7398,-1).

Formula

a(n) = 7398*a(n-1)-a(n-2).

G.f.: -5*(x-1) / (x^2-7398*x+1).

Mathematica

LinearRecurrence[{7398, -1}, {5, 36985}, 20] (* Harvey P. Dale, Jan 14 2015 *)

Prog

(PARI) Vec(-5*(x-1)/(x^2-7398*x+1) + O(x^30))

Crossrefs

Cf. A228546 gives the corresponding x-values.

Sequence in context: A246870 A193366 A347934 * A193148 A307492 A355959

Adjacent sequences: A228544 A228545 A228546 * A228548 A228549 A228550

Keyword

nonn,easy

Author

Colin Barker, Aug 25 2013

Status

approved