A042015 Denominators of continued fraction convergents to sqrt(531).

1, 23, 1059, 24380, 1122539, 25842777, 1189890281, 27393319240, 1261282575321, 29036892551623, 1336958339949979, 30779078711401140, 1417174579064402419, 32625794397192656777, 1502203716849926614161, 34583311281945504782480, 1592334522686343146608241

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, 1060, 0, -1).

Formula

G.f.: -(x^2-23*x-1) / (x^4-1060*x^2+1). - Colin Barker, Nov 29 2013

a(n) = 1060*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Jan 12 2014

Mathematica

Denominator[Convergents[Sqrt[531], 40]] (* Vincenzo Librandi, Jan 12 2014 *)
LinearRecurrence[{0, 1060, 0, -1}, {1, 23, 1059, 24380}, 20] (* Harvey P. Dale, Oct 06 2023 *)

Prog

(Magma) I:=[1, 23, 1059, 24380]; [n le 4 select I[n] else 1060*Self(n-2)-Self(n-4): n in [1..20]]; // Vincenzo Librandi, Jan 12 2014

Crossrefs

Cf. A042014, A040507.

Sequence in context: A130551 A069479 A174748 * A042012 A128404 A126741

Adjacent sequences: A042012 A042013 A042014 * A042016 A042017 A042018

Keyword

nonn,frac,easy,less

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Nov 29 2013

Status

approved