



678, 2708, 6090, 10824, 16910, 24348, 33138, 43280, 54774, 67620, 81818, 97368, 114270, 132524, 152130, 173088, 195398, 219060, 244074, 270440, 298158, 327228, 357650, 389424, 422550, 457028, 492858, 530040, 568574, 608460, 649698, 692288
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OFFSET

1,1


COMMENTS

The identity (676*n+1)^2(676*n^2+2*n)*(26)^2=1 can be written as A158386(n)^2a(n)*(26)^2=1.


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Vincenzo Librandi, X^2AY^2=1
E. J. Barbeau, Polynomial Excursions, Chapter 10: Diophantine equations (2010), pages 8485 (row 15 in the first table at p. 85, case d(t) = t*(26^2*t+2)).
Index to sequences with linear recurrences with constant coefficients, signature (3,3,1).


FORMULA

a(n) = 3*a(n1) 3*a(n2) +a(n3).
G.f.: x*(678+674*x)/(1x)^3.


MATHEMATICA

LinearRecurrence[{3, 3, 1}, {678, 2708, 6090}, 50]


PROG

(MAGMA) I:=[678, 2708, 6090]; [n le 3 select I[n] else 3*Self(n1)3*Self(n2)+1*Self(n3): n in [1..50]];
(PARI) a(n) = 676*n^2 + 2*n.


CROSSREFS

Cf. A158386.
Sequence in context: A144381 A097773 A031524 * A251836 A251830 A250872
Adjacent sequences: A158382 A158383 A158384 * A158386 A158387 A158388


KEYWORD

nonn,easy


AUTHOR

Vincenzo Librandi, Mar 17 2009


STATUS

approved



