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A154295
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81n^2 - 90n + 26.
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4
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26, 17, 170, 485, 962, 1601, 2402, 3365, 4490, 5777, 7226, 8837, 10610, 12545, 14642, 16901, 19322, 21905, 24650, 27557, 30626, 33857, 37250, 40805, 44522, 48401, 52442, 56645, 61010, 65537, 70226, 75077, 80090, 85265, 90602, 96101, 101762
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| The identity (81n^2+72n+17)^2-(9n^2+8n+2)*(27n+12)^2=1 can be written as a(n+1)^2-A154262(n+1)*A154266(n)^2=1. - Vincenzo Librandi, Feb 03 2012
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = A002522(|9n-5|). - R. J. Mathar, Jan 07 2009
G.f.: (-26+61*x-197*x^2)/(x-1)^3. - Vincenzo Librandi, Feb 03 2012
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Vincenzo Librandi, Feb 03 2012
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {26, 17, 170}, 40] (* Vincenzo Librandi, Feb 03 2012 *)
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PROG
| (MAGMA) I:=[26, 17, 170]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 03 2012
(PARI) for(n=0, 22, print1(81*n^2-90*n+26", ")); \\ Vincenzo Librandi, Feb 03 2012
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CROSSREFS
| Cf. A154262, A154266.
Sequence in context: A131083 A203597 A040652 * A072360 A093538 A022982
Adjacent sequences: A154292 A154293 A154294 * A154296 A154297 A154298
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KEYWORD
| nonn,easy,changed
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 06 2009
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EXTENSIONS
| Corrected by Don Reble, Jun 16 2010
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