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A041757 Denominators of continued fraction convergents to sqrt(398). 2
1, 1, 19, 20, 779, 799, 15161, 15960, 621641, 637601, 12098459, 12736060, 496068739, 508804799, 9654555121, 10163359920, 395862232081, 406025592001, 7704322888099, 8110348480100, 315897565131899, 324007913611999, 6148040010147881, 6472047923759880 (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 (0,0,0,798,0,0,0,-1).

FORMULA

G.f.: -(x^2-x-1)*(x^4+20*x^2+1) / (x^8-798*x^4+1). - Colin Barker, Nov 24 2013

a(n) = 798*a(n-4) - a(n-8) for n>7. - Vincenzo Librandi, Dec 24 2013

MATHEMATICA

Denominator[Convergents[Sqrt[398], 30]] (* Vincenzo Librandi, Dec 24 2013 *)

PROG

(MAGMA) I:=[1, 1, 19, 20, 779, 799, 15161, 15960]; [n le 8 select I[n] else 798*Self(n-4)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Dec 24 2013

CROSSREFS

Cf. A041756, A040378.

Sequence in context: A197353 A041179 A041756 * A041758 A042735 A156758

Adjacent sequences:  A041754 A041755 A041756 * A041758 A041759 A041760

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Nov 24 2013

STATUS

approved

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Last modified July 5 01:46 EDT 2020. Contains 335457 sequences. (Running on oeis4.)