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258, 1028, 2310, 4104, 6410, 9228, 12558, 16400, 20754, 25620, 30998, 36888, 43290, 50204, 57630, 65568, 74018, 82980, 92454, 102440, 112938, 123948, 135470, 147504, 160050, 173108, 186678, 200760, 215354, 230460, 246078, 262208, 278850, 296004
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (256*n+1)^2-(256*n^2+2*n)*(16)^2=1 can be written as A158231(n)^2-a(n)*(16)^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*(16^2*t+2)).
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).
G.f.: x*(-254*x-258)/(x-1)^3.
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {258, 1028, 2310}, 50]
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PROG
| (MAGMA) I:=[258, 1028, 2310]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..50]];
(PARI) a(n) = 256*n^2+2*n.
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CROSSREFS
| Cf. A158231.
Sequence in context: A031514 A173981 A202892 * A168125 A097734 A121915
Adjacent sequences: A158227 A158228 A158229 * A158231 A158232 A158233
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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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