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A041423 Denominators of continued fraction convergents to sqrt(227). 2
1, 15, 451, 6780, 203851, 3064545, 92140201, 1385167560, 41647167001, 626092672575, 18824427344251, 282992502836340, 8508599512434451, 127911985189353105, 3845868155193027601, 57815934313084767120, 1738323897547736041201 (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 (0,452,0,-1).

FORMULA

G.f.: -(x^2-15*x-1) / (x^4-452*x^2+1). - Colin Barker, Nov 17 2013

a(n) = 452*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 17 2013

MATHEMATICA

Denominator[Convergents[Sqrt[227], 20]] (* Harvey P. Dale, Jul 13 2013 *)

CoefficientList[Series[(1 + 15 x - x^2)/(x^4 - 452 x^2 + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 17 2013 *)

PROG

(MAGMA) I:=[1, 15, 451, 6780]; [n le 4 select I[n] else 452*Self(n-2)-Self(n-4): n in [1..100]]; // Vincenzo Librandi, Dec 17 2013

CROSSREFS

Cf. A041422, A040211.

Sequence in context: A267643 A267666 A020285 * A041420 A036506 A219561

Adjacent sequences:  A041420 A041421 A041422 * A041424 A041425 A041426

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 22 09:40 EST 2019. Contains 320390 sequences. (Running on oeis4.)