A174773 y-values in the solution to x^2 - 34*y^2 = 1.

0, 6, 420, 29394, 2057160, 143971806, 10075969260, 705173876394, 49352095378320, 3453941502606006, 241726553087042100, 16917404774590340994, 1183976607668236827480, 82861445132001987582606

Offset

1,2

Comments

The corresponding values of x of this Pell equation are in A174749.

Links

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

Index entries for linear recurrences with constant coefficients, signature (70,-1).

Formula

a(n) = 70*a(n-1)-a(n-2) with a(1)=0, a(2)=6.

G.f.: 6*x^2/(1-70*x+x^2).

Mathematica

LinearRecurrence[{70, -1}, {0, 6}, 30]

Prog

I:=[0, 6]; [n le 2 select I[n] else 70*Self(n-1)-Self(n-2): n (Magma) in [1..20]];
(PARI) a(n)=([0, 1; -1, 70]^(n-1)*[0; 6])[1, 1] \\ Charles R Greathouse IV, Jan 29 2016

Crossrefs

Cf. A174749.

Sequence in context: A331352 A159015 A106206 * A229471 A258192 A273820

Adjacent sequences: A174770 A174771 A174772 * A174774 A174775 A174776

Keyword

nonn,easy

Author

Vincenzo Librandi, Apr 15 2010

Status

approved