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A158412 961n - 1. 2
960, 1921, 2882, 3843, 4804, 5765, 6726, 7687, 8648, 9609, 10570, 11531, 12492, 13453, 14414, 15375, 16336, 17297, 18258, 19219, 20180, 21141, 22102, 23063, 24024, 24985, 25946, 26907, 27868, 28829, 29790, 30751, 31712, 32673, 33634 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The identity (961*n-1)^2-(961*n^2-2*n)*(31)^2=1 can be written as a(n)^2-A158410(n)*(31)^2=1.

LINKS

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

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

E. J. Barbeau, Polynomial Excursions, Chapter 10: Diophantine equations (2010), pages 84-85 (row 15 in the first table at p. 85, case d(t) = t*(31^2*t-2)).

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

FORMULA

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

G.f.: x*(960+x)/(1-x)^2.

MATHEMATICA

LinearRecurrence[{2, -1}, {960, 1921}, 50]

PROG

(MAGMA) I:=[960, 1921]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];

(PARI) a(n) = 961*n - 1.

CROSSREFS

Cf. A158410.

Sequence in context: A257417 A137491 A179672 * A247723 A057666 A046788

Adjacent sequences:  A158409 A158410 A158411 * A158413 A158414 A158415

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 18 2009

STATUS

approved

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Last modified August 19 18:33 EDT 2019. Contains 326133 sequences. (Running on oeis4.)