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

Author

Vincenzo Librandi, Apr 14 2010

Keywords

• nonn
• easy

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).

Crossrefs

Cf. A114049.

Programs

Magma

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

Mathematica

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

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).