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A041623 Denominators of continued fraction convergents to sqrt(330). 2
1, 6, 217, 1308, 47305, 285138, 10312273, 62158776, 2248028209, 13550328030, 490059837289, 2953909351764, 106830796500793, 643938688356522, 23288623577335585, 140375680152370032, 5076813109062656737, 30601254334528310454, 1106721969152081833081 (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 (0,218,0,-1).

FORMULA

G.f.: -(x^2-6*x-1) / (x^4-218*x^2+1). - Colin Barker, Nov 20 2013

a(n) = 218*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 22 2013

MATHEMATICA

Denominator[Convergents[Sqrt[330], 30]] (* Vincenzo Librandi, Dec 22 2013 *)

LinearRecurrence[{0, 218, 0, -1}, {1, 6, 217, 1308}, 20] (* Harvey P. Dale, Sep 23 2018 *)

PROG

(MAGMA) I:=[1, 6, 217, 1308]; [n le 4 select I[n] else 218*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 22 2013

CROSSREFS

Cf. A041622, A040311.

Sequence in context: A194503 A229869 A234610 * A292692 A015477 A144658

Adjacent sequences:  A041620 A041621 A041622 * A041624 A041625 A041626

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Nov 20 2013

STATUS

approved

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Last modified November 17 00:08 EST 2019. Contains 329209 sequences. (Running on oeis4.)