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A042921 Denominators of continued fraction convergents to sqrt(992). 2
1, 2, 125, 252, 15749, 31750, 1984249, 4000248, 249999625, 503999498, 31497968501, 63499936500, 3968494031501, 8000487999502, 499998750000625, 1007997988000752, 62995874006047249, 126999746000095250, 7936980126011952749, 16000959998024000748 (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, 126, 0, -1).

FORMULA

G.f.: -(x^2-2*x-1) / (x^4-126*x^2+1). - Colin Barker, Dec 25 2013

a(n) = 126*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Feb 01 2014

MATHEMATICA

Denominator[Convergents[Sqrt[992], 30]] (* Vincenzo Librandi, Feb 01 2014 *)

PROG

(Magma) I:=[1, 2, 125, 252]; [n le 4 select I[n] else 126*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Feb 01 2014

CROSSREFS

Cf. A042920, A040960.

Sequence in context: A065705 A012870 A183720 * A123006 A028481 A049659

Adjacent sequences: A042918 A042919 A042920 * A042922 A042923 A042924

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Colin Barker, Dec 25 2013

STATUS

approved

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Last modified November 29 16:39 EST 2022. Contains 358431 sequences. (Running on oeis4.)