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27223, 108896, 245019, 435592, 680615, 980088, 1334011, 1742384, 2205207, 2722480, 3294203, 3920376, 4600999, 5336072, 6125595, 6969568, 7867991, 8820864, 9828187, 10889960, 12006183, 13176856, 14401979, 15681552, 17015575
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (1482401250*n^2-108900*n+1)^2-(27225*n^2-2*n)*(8984250*n-330)^2=1 can be written as A157816(n)^2-a(n)* A157815(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*(27223+27227*x)/(1-x)^3.
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {27223, 108896, 245019}, 40]
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PROG
| (MAGMA) I:=[27223, 108896, 245019]; [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) = 27225*n^2 - 2*n.
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CROSSREFS
| Cf. A157815, A157816.
Sequence in context: A037045 A186481 A127411 * A157820 A032746 A099230
Adjacent sequences: A157811 A157812 A157813 * A157815 A157816 A157817
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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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