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A158250 256n - 1. 2
255, 511, 767, 1023, 1279, 1535, 1791, 2047, 2303, 2559, 2815, 3071, 3327, 3583, 3839, 4095, 4351, 4607, 4863, 5119, 5375, 5631, 5887, 6143, 6399, 6655, 6911, 7167, 7423, 7679, 7935, 8191, 8447, 8703, 8959, 9215, 9471, 9727, 9983, 10239, 10495 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The identity (256*n-1)^2-(256*n^2-2*n)*(16)^2=1 can be written as a(n)^2-A158249(n)*(16)^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*(16^2*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*(255+x)/(1-x)^2.

MATHEMATICA

LinearRecurrence[{2, -1}, {255, 511}, 50]

PROG

(MAGMA) I:=[255, 511]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];

(PARI) a(n) = 256*n - 1.

CROSSREFS

Cf. A158249.

Sequence in context: A043348 A031469 A045065 * A045137 A329489 A045113

Adjacent sequences:  A158247 A158248 A158249 * A158251 A158252 A158253

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 15 2009

STATUS

approved

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Last modified July 30 23:12 EDT 2021. Contains 346365 sequences. (Running on oeis4.)