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A157844
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103680000n^2 - 161251200n + 62697601.
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3
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5126401, 154915201, 512064001, 1076572801, 1848441601, 2827670401, 4014259201, 5408208001, 7009516801, 8818185601, 10834214401, 13057603201, 15488352001, 18126460801, 20971929601, 24024758401, 27284947201, 30752496001
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (103680000*n^2-161251200*n+62697601)^2-(3600*n^2-5599*n+2177)*(1728000*n-1343760)^2=1 can be written as a(n)^2-A157842(n)*A157843(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
| a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).
G.f.: x*(-5126401-139535998*x-62697601*x^2)/(x-1)^3.
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {5126401, 154915201, 512064001}, 40]
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PROG
| (MAGMA) I:=[5126401, 154915201, 512064001]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];
(PARI) a(n) = 103680000*n^2 - 161251200*n + 62697601.
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CROSSREFS
| Cf. A157842, A157843.
Sequence in context: A015363 A206136 A186624 * A140658 A172715 A125780
Adjacent sequences: A157841 A157842 A157843 * A157845 A157846 A157847
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KEYWORD
| nonn,easy
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 07 2009
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