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A157862
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1728000n + 240.
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3
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1728240, 3456240, 5184240, 6912240, 8640240, 10368240, 12096240, 13824240, 15552240, 17280240, 19008240, 20736240, 22464240, 24192240, 25920240, 27648240, 29376240, 31104240, 32832240, 34560240, 36288240, 38016240
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (103680000*n^2+28800*n+1)^2-(3600*n^2+n)*(1728000*n+240)^2=1 can be written as A157863(n)^2-A157861(n)*a(n)^2=1. - Vincenzo Librandi, Jan 25 2012
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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 (2,-1).
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FORMULA
| G.f.: x*(1728240-240*x)/(1-x)^2. - Colin Barker, Jan 17 2012
a(n) = 2*a(n-1)-a(n-2). - Vincenzo Librandi, Jan 25 2012
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MATHEMATICA
| LinearRecurrence[{2, -1}, {1728240, 3456240}, 40] (* Vincenzo Librandi, Jan 25 2012 *)
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PROG
| (MAGMA) I:=[1728240, 3456240]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..30]]; // Vincenzo Librandi, Jan 25 2012
(PARI) for(n=1, 22, print1(1728000*n + 240", ")); \\ Vincenzo Librandi, Jan 25 2012
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CROSSREFS
| Cf. A157861, A157863.
Sequence in context: A151639 A083646 A157858 * A186586 A131639 A187139
Adjacent sequences: A157859 A157860 A157861 * A157863 A157864 A157865
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KEYWORD
| nonn,easy
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 08 2009
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