A174745 y-values in the solution to x^2 - 21*y^2 = 1.

0, 12, 1320, 145188, 15969360, 1756484412, 193197315960, 21249948271188, 2337301112514720, 257081872428348012, 28276668666005766600, 3110176471388205977988, 342091135184036651812080

Offset

1,2

Comments

The corresponding values of x of this Pell equation are in A114049.

Links

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

Index entries for linear recurrences with constant coefficients, signature (110,-1).

Formula

a(n) = 110*a(n-1)-a(n-2) with a(1)=0, a(2)=12.

G.f.: 12*x^2/(1-110*x+x^2).

Mathematica

LinearRecurrence[{110, -1}, {0, 12}, 30]

Prog

(Magma) I:=[0, 12]; [n le 2 select I[n] else 110*Self(n-1)-Self(n-2): n in [1..20]];

Crossrefs

Cf. A114049.

Sequence in context: A137343 A133461 A246981 * A071309 A067108 A240627

Adjacent sequences: A174742 A174743 A174744 * A174746 A174747 A174748

Keyword

nonn,easy

Author

Vincenzo Librandi, Apr 14 2010

Status

approved