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226, 451, 676, 901, 1126, 1351, 1576, 1801, 2026, 2251, 2476, 2701, 2926, 3151, 3376, 3601, 3826, 4051, 4276, 4501, 4726, 4951, 5176, 5401, 5626, 5851, 6076, 6301, 6526, 6751, 6976, 7201, 7426, 7651, 7876, 8101, 8326, 8551, 8776, 9001, 9226, 9451, 9676
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (225*n+1)^2-(225*n^2+2*n)*(15)^2=1 can be written as a(n)^2-A158228(n)*(15)^2=1.
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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*(15^2*t+2)).
Index to sequences with linear recurrences with constant coefficients, signature (2,-1).
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FORMULA
| a(n) = 2*a(n-1)-a(n-2).
G.f.: x*(226-x)/(1-x)^2.
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MATHEMATICA
| LinearRecurrence[{2, -1}, {226, 451}, 50]
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PROG
| (MAGMA) I:=[226, 451]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
(PARI) a(n) = 225*n + 1.
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CROSSREFS
| Cf. A158228.
Sequence in context: A043670 A126897 A067265 * A031708 A156814 A031603
Adjacent sequences: A158226 A158227 A158228 * A158230 A158231 A158232
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KEYWORD
| nonn,easy
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 14 2009
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