



168, 337, 506, 675, 844, 1013, 1182, 1351, 1520, 1689, 1858, 2027, 2196, 2365, 2534, 2703, 2872, 3041, 3210, 3379, 3548, 3717, 3886, 4055, 4224, 4393, 4562, 4731, 4900, 5069, 5238, 5407, 5576, 5745, 5914, 6083, 6252, 6421, 6590, 6759, 6928, 7097, 7266
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OFFSET

1,1


COMMENTS

The identity (169*n1)^2(1169*n^22*n)*(13)^2=1 can be written as a(n)^2A158218(n)*(13)^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*(13^2*t2)).
Index entries for linear recurrences with constant coefficients, signature (2,1).


FORMULA

a(n) = 2*a(n1)a(n2).
G.f.: x*(168+x)/(1x)^2.


MATHEMATICA

LinearRecurrence[{2, 1}, {168, 337}, 50]
169*Range[50]1 (* Harvey P. Dale, Mar 17 2018 *)


PROG

(Magma) I:=[168, 337]; [n le 2 select I[n] else 2*Self(n1)Self(n2): n in [1..50]];
(PARI) a(n) = 169*n  1.


CROSSREFS

Cf. A158218.
Sequence in context: A008890 A230479 A105915 * A273771 A210207 A303082
Adjacent sequences: A158216 A158217 A158218 * A158220 A158221 A158222


KEYWORD

nonn,easy


AUTHOR

Vincenzo Librandi, Mar 14 2009


STATUS

approved



