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A158393
a(n) = 676*n - 1.
2
675, 1351, 2027, 2703, 3379, 4055, 4731, 5407, 6083, 6759, 7435, 8111, 8787, 9463, 10139, 10815, 11491, 12167, 12843, 13519, 14195, 14871, 15547, 16223, 16899, 17575, 18251, 18927, 19603, 20279, 20955, 21631, 22307, 22983, 23659, 24335
OFFSET
1,1
COMMENTS
The identity (676*n-1)^2-(676*n^2-2*n)*(26)^2=1 can be written as a(n)^2-A158392(n)*(26)^2=1.
LINKS
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*(26^2*t-2)).
FORMULA
a(n) = 2*a(n-1)-a(n-2).
G.f.: x*(675+x)/(1-x)^2.
MATHEMATICA
LinearRecurrence[{2, -1}, {675, 1351}, 50]
PROG
(Magma) I:=[675, 1351]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
(PARI) a(n) = 676*n - 1.
CROSSREFS
Cf. A158392.
Sequence in context: A158392 A264328 A124942 * A294949 A159208 A358174
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 18 2009
STATUS
approved