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A042307 Denominators of continued fraction convergents to sqrt(680). 2
1, 13, 677, 8814, 459005, 5975879, 311204713, 4051637148, 210996336409, 2747004010465, 143055204880589, 1862464667458122, 96991217912702933, 1262748297532596251, 65759902689607707985, 856141483262432800056, 44585117032336113310897 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (0,678,0,-1).

FORMULA

G.f.: -(x^2-13*x-1) / ((x^2-26*x-1)*(x^2+26*x-1)). - Colin Barker, Dec 07 2013

a(n) = 678*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Jan 19 2014

MATHEMATICA

Denominator[Convergents[Sqrt[680], 30]] (* Vincenzo Librandi, Jan 19 2014 *)

PROG

(Magma) I:=[1, 13, 677, 8814]; [n le 4 select I[n] else 678*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Jan 19 2014

CROSSREFS

Cf. A042306, A040653.

Sequence in context: A092547 A298951 A157027 * A012746 A211094 A290166

Adjacent sequences:  A042304 A042305 A042306 * A042308 A042309 A042310

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Dec 07 2013

STATUS

approved

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Last modified October 4 21:22 EDT 2022. Contains 357240 sequences. (Running on oeis4.)