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A157858
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1728000n - 240.
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3
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1727760, 3455760, 5183760, 6911760, 8639760, 10367760, 12095760, 13823760, 15551760, 17279760, 19007760, 20735760, 22463760, 24191760, 25919760, 27647760, 29375760, 31103760, 32831760, 34559760, 36287760, 38015760
(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 A157859(n)^2-A157857(n)*a(n)^2=1. - Vincenzo Librandi, Jan 25 2012
This is the case s=60 of the identity (8*n^2*s^4-8*n*s^2+1)^2 - (n^2*s^2-n)*(8*n*s^3-4*s)^2 = 1. - Bruno Berselli, 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*(1727760+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}, {1727760, 3455760}, 40] (* Vincenzo Librandi, Jan 25 2012 *)
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PROG
| (MAGMA) I:=[1727760, 3455760]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]]; // 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. A157857, A157859.
Sequence in context: A121887 A151639 A083646 * A157862 A186586 A131639
Adjacent sequences: A157855 A157856 A157857 * A157859 A157860 A157861
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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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