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306, 1278, 2898, 5166, 8082, 11646, 15858, 20718, 26226, 32382, 39186, 46638, 54738, 63486, 72882, 82926, 93618, 104958, 116946, 129582, 142866, 156798, 171378, 186606, 202482, 219006, 236178, 253998, 272466, 291582, 311346, 331758
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (36*n^2-1)^2-(324*n^2-18)*(2*n)^2 = 1 can be written as A136017(n)^2-a(n)* A005843(n)^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
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| G.f.: -18*x*(17+20*x-x^2)/(x-1)^3. - Vincenzo Librandi, Feb 16 2012
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Vincenzo Librandi, Feb 16 2012
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {306, 1278, 2898}, 40] (* Vincenzo Librandi, Feb 16 2012 *)
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PROG
| (MAGMA) I:=[306, 1278, 2898]; [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 16 2012
(PARI) for(n=1, 40, print1(324*n^2 - 18", ")); \\ Vincenzo Librandi, Feb 16 2012
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CROSSREFS
| Cf. A005843, A136017.
Sequence in context: A156168 A005951 A206271 * A030030 A206679 A172966
Adjacent sequences: A158586 A158587 A158588 * A158590 A158591 A158592
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KEYWORD
| nonn,easy,changed
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 22 2009
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EXTENSIONS
| Comment rewritten by R. J. Mathar, Oct 28 2009
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