A174776 y-values in the solution to x^2 - 39*y^2 = 1.

0, 4, 200, 9996, 499600, 24970004, 1248000600, 62375059996, 3117504999200, 155812874900004, 7787526240001000, 389220499125149996, 19453237430017498800, 972272651001749790004, 48594179312657472001400

Offset

1,2

Comments

The corresponding values of x of this Pell equation are in A174751.

Links

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

Index entries for linear recurrences with constant coefficients, signature (50,-1).

Formula

a(n) = 50*a(n-1)-a(n-2) with a(1)=0, a(2)=4.

G.f.: 4*x^2/(1-50*x+x^2).

Mathematica

LinearRecurrence[{50, -1}, {0, 4}, 30]

Prog

(Magma) I:=[0, 4]; [n le 2 select I[n] else 50*Self(n-1)-Self(n-2): n in [1..20]];

Crossrefs

Cf. A174751.

Sequence in context: A156235 A356214 A034862 * A216932 A317273 A049656

Adjacent sequences: A174773 A174774 A174775 * A174777 A174778 A174779

Keyword

nonn,easy

Author

Vincenzo Librandi, Apr 15 2010

Status

approved