A174778 y-values in the solution to x^2 - 41*y^2 = 1.

0, 320, 1311360, 5373952960, 22022457918720, 90248027176961600, 369836393348730718080, 1515589449695071305730240, 6210885195014008862151805440, 25452206013577958622026792962880

Offset

1,2

Comments

The corresponding values of x of this Pell equation are in A174752.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (4098,-1).

Formula

a(n) = 4098*a(n-1)-a(n-2) with a(1)=0, a(2)=320.

G.f.: 320*x^2/(1-4098*x+x^2).

Mathematica

LinearRecurrence[{4098, -1}, {0, 320}, 30]

Prog

(Magma) I:=[0, 320]; [n le 2 select I[n] else 4098*Self(n-1)-Self(n-2): n in [1..20]];

Crossrefs

Cf. A174752.

Sequence in context: A045813 A121011 A264063 * A300849 A351994 A261262

Adjacent sequences: A174775 A174776 A174777 * A174779 A174780 A174781

Keyword

nonn,easy

Author

Vincenzo Librandi, Apr 15 2010

Status

approved