A041927 Denominators of continued fraction convergents to sqrt(486).

1, 22, 969, 21340, 939929, 20699778, 911730161, 20078763320, 884377316241, 19476379720622, 857845085023609, 18892068250240020, 832108848095584489, 18325286726353098778, 807144724807631930721, 17775509232494255574640

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,970,0,-1).

Formula

G.f.: -(x^2 -22*x -1) / (x^4 -970*x^2 +1). - Colin Barker, Nov 27 2013

a(n) = 970*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 27 2013

Mathematica

Denominator[Convergents[Sqrt[486], 30]] (* Vincenzo Librandi, Dec 27 2013 *)
LinearRecurrence[{0, 970, 0, -1}, {1, 22, 969, 21340}, 20] (* Harvey P. Dale, Feb 06 2017 *)

Prog

(Magma) I:=[1, 22, 969, 21340]; [n le 4 select I[n] else 970*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 27 2013

Crossrefs

Cf. A041926, A040463.

Sequence in context: A200575 A102995 A211887 * A041924 A160139 A004633

Adjacent sequences: A041924 A041925 A041926 * A041928 A041929 A041930

Keyword

nonn,frac,easy,less

Author

N. J. A. Sloane.

Status

approved