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A041775
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Denominators of continued fraction convergents to sqrt(408).
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2
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1, 5, 201, 1010, 40601, 204015, 8201201, 41210020, 1656602001, 8324220025, 334625403001, 1681451235030, 67592674804201, 339644825256035, 13653385685045601, 68606573250484040, 2757916315704407201, 13858188151772520045, 557085442386605209001
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OFFSET
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0,2
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,202,0,-1).
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FORMULA
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G.f.: -(x^2-5*x-1) / (x^4-202*x^2+1). - Colin Barker, Nov 24 2013
a(n) = 202*a(n-2) - a(n-4). for n>3. - Vincenzo Librandi, Dec 24 2013
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MATHEMATICA
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Denominator[Convergents[Sqrt[408], 30]] (* Vincenzo Librandi, Dec 24 2013 *)
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PROG
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(MAGMA) I:=[1, 5, 201, 1010]; [n le 4 select I[n] else 202*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 24 2013
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CROSSREFS
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Cf. A041774, A040387.
Sequence in context: A128791 A303136 A244848 * A093976 A337579 A196799
Adjacent sequences: A041772 A041773 A041774 * A041776 A041777 A041778
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KEYWORD
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nonn,frac,easy
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from Colin Barker, Nov 24 2013
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STATUS
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approved
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