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A041401 Denominators of continued fraction convergents to sqrt(215). 2
1, 1, 2, 3, 86, 89, 175, 264, 7567, 7831, 15398, 23229, 665810, 689039, 1354849, 2043888, 58583713, 60627601, 119211314, 179838915, 5154700934, 5334539849, 10489240783, 15823780632, 453555098479, 469378879111, 922933977590, 1392312856701, 39907693965218 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 88, 0, 0, 0, -1).

FORMULA

G.f.: -(x^2-x-1)*(x^4+3*x^2+1) / (x^8-88*x^4+1). - Colin Barker, Nov 17 2013

a(n) = 88*a(n-4) - a(n-8) for n>7. - Vincenzo Librandi, Dec 17 2013

MATHEMATICA

Denominator[Convergents[Sqrt[215], 30]] (* Harvey P. Dale, Oct 11 2012 *)

CoefficientList[Series[(1 + x - x^2) (x^4 + 3 x^2 + 1)/(x^8 - 88 x^4 + 1), {x, 0, 40}], x] (* Vincenzo Librandi, Dec 17 2013 *)

PROG

(MAGMA) I:=[1, 1, 2, 3, 86, 89, 175, 264]; [n le 8 select I[n] else 88*Self(n-4)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Dec 17 2013

CROSSREFS

Cf. A041400, A040200.

Sequence in context: A182343 A242370 A153228 * A103013 A246121 A224934

Adjacent sequences:  A041398 A041399 A041400 * A041402 A041403 A041404

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Nov 17 2013

STATUS

approved

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Last modified February 19 10:24 EST 2019. Contains 320310 sequences. (Running on oeis4.)