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A041149 Denominators of continued fraction convergents to sqrt(84). 2
1, 6, 109, 660, 11989, 72594, 1318681, 7984680, 145042921, 878242206, 15953402629, 96598657980, 1754729246269, 10624974135594, 193004263686961, 1168650556257360, 21228714276319441, 128540936214174006, 2334965566131451549, 14138334333002883300 (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 (0,110,0,-1).

FORMULA

G.f.: -(x^2-6*x-1) / (x^4-110*x^2+1). - Colin Barker, Nov 13 2013

a(n) = 110*a(n-2) - a(n-4). - Vincenzo Librandi, Dec 11 2013

MATHEMATICA

Denominator/@Convergents[Sqrt[84], 50] (* Vladimir Joseph Stephan Orlovsky, Jul 05 2011 *)

CoefficientList[Series[(1 + 6 x - x^2)/(x^4 - 110 x^2 + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 11 2013 *)

PROG

(MAGMA) I:=[1, 6, 109, 660]; [n le 4 select I[n] else 110*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 11 2013

CROSSREFS

Cf. A041148, A040074, A020841, A010535.

Sequence in context: A168482 A132856 A288629 * A193810 A217987 A119814

Adjacent sequences:  A041146 A041147 A041148 * A041150 A041151 A041152

KEYWORD

nonn,cofr,frac,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified December 13 09:58 EST 2019. Contains 329968 sequences. (Running on oeis4.)