A042779 Denominators of continued fraction convergents to sqrt(920).

1, 3, 181, 546, 32941, 99369, 5995081, 18084612, 1091071801, 3291300015, 198569072701, 598998518118, 36138480159781, 109014438997461, 6577004820007441, 19840028899019784, 1196978738761194481, 3610776245182603227, 217843553449717388101, 657141436594334767530

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,182,0,-1).

Formula

G.f.: -(x^2-3*x-1) / (x^4-182*x^2+1). - Colin Barker, Dec 23 2013

a(n) = 182*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Jan 29 2014

Mathematica

Denominator[Convergents[Sqrt[920], 30]] (* Harvey P. Dale, May 03 2012 *)

Prog

(Magma) I:=[1, 3, 181, 546]; [n le 4 select I[n] else 182*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Jan 29 2014

Crossrefs

Cf. A042778, A040889.

Sequence in context: A093434 A053291 A013519 * A103503 A203562 A371153

Adjacent sequences: A042776 A042777 A042778 * A042780 A042781 A042782

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Dec 23 2013

Status

approved