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A158414
961n + 1.
2
962, 1923, 2884, 3845, 4806, 5767, 6728, 7689, 8650, 9611, 10572, 11533, 12494, 13455, 14416, 15377, 16338, 17299, 18260, 19221, 20182, 21143, 22104, 23065, 24026, 24987, 25948, 26909, 27870, 28831, 29792, 30753, 31714, 32675, 33636
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-A158413(n)*(31)^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*(31^2*t+2)).
FORMULA
G.f.: x*(962-x)/(1-x)^2.
a(n) = 2*a(n-1)-a(n-2).
MATHEMATICA
LinearRecurrence[{2, -1}, {962, 1923}, 50]
PROG
(Magma) I:=[962, 1923]; [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. A158413.
Sequence in context: A231761 A098207 A304315 * A031740 A031529 A347884
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 18 2009
STATUS
approved