A157787 8984250n - 2515920.

6468330, 15452580, 24436830, 33421080, 42405330, 51389580, 60373830, 69358080, 78342330, 87326580, 96310830, 105295080, 114279330, 123263580, 132247830, 141232080, 150216330, 159200580, 168184830, 177169080, 186153330, 195137580

Offset

1,1

Comments

The identity (1482401250*n^2-830253600*n +116250751)^2-(27225*n^2-15248*n +2135) *(8984250*n -2515920)^2=1 can be written as A157788(n)^2-A157786(n)*a(n)^2=1.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Vincenzo Librandi, X^2-AY^2=1

Index entries for linear recurrences with constant coefficients, signature (2,-1).

Formula

a(n) = 2*a(n-1) -a(n-2).

G.f: x*(6468330+2515920*x)/(x-1)^2.

Mathematica

Table[8984250n-2515920, {n, 30}].
LinearRecurrence[{2, -1}, {6468330, 15452580}, 30] (* Harvey P. Dale, Mar 29 2015 *)

Prog

(Magma) I:=[6468330, 15452580]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..30]];
(PARI) a(n) = 8984250*n - 2515920.

Crossrefs

Cf. A157786, A157788.

Sequence in context: A254097 A209950 A288074 * A115615 A257016 A234090

Adjacent sequences: A157784 A157785 A157786 * A157788 A157789 A157790

Keyword

nonn,easy

Author

Vincenzo Librandi, Mar 06 2009

Status

approved