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18, 342, 1314, 2934, 5202, 8118, 11682, 15894, 20754, 26262, 32418, 39222, 46674, 54774, 63522, 72918, 82962, 93654, 104994, 116982, 129618, 142902, 156834, 171414, 186642, 202518, 219042, 236214, 254034, 272502, 291618, 311382, 331794
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| The identity (36*n^2+1)^2-(324*n^2+18)*(2*n)^2 = 1 can be written as A158591(n)^2-a(n)* A005843(n)^2 =1.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..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*(1+16*x+19*x^2)/(x-1)^3.
a(n)= 3*a(n-1) -3*a(n-2) +a(n-3).
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {18, 342, 1314}, 50] (* Vincenzo Librandi, Feb 16 2012 *)
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PROG
| (MAGMA) I:=[18, 342, 1314]; [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=0, 40, print1(324*n^2 + 18", ")); \\ Vincenzo Librandi, Feb 16 2012
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CROSSREFS
| Cf. A005843, A158591.
Sequence in context: A166787 A068771 A039646 * A143168 A127585 A182609
Adjacent sequences: A158587 A158588 A158589 * A158591 A158592 A158593
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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, formula replaced by R. J. Mathar, Oct 28 2009
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