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A157769

a(n) = 8984250*n - 6468330.

2515920, 11500170, 20484420, 29468670, 38452920, 47437170, 56421420, 65405670, 74389920, 83374170, 92358420, 101342670, 110326920, 119311170, 128295420, 137279670, 146263920, 155248170, 164232420, 173216670, 182200920, 191185170

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OFFSET

1,1

COMMENTS

The identity (1482401250*n^2-2134548900*n+768398401)^2-(27225*n^2-39202*n+14112) *(8984250*n-6468330)^2=1 can be written as A157770(n)^2-A157768(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*(2515920+6468330*x)/(x-1)^2.

MATHEMATICA

Table[8984250*n-6468330, {n, 30}]

PROG

(Magma) I:=[2515920, 11500170]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..30]];

(PARI) a(n) = 8984250*n - 6468330