A041931 Denominators of continued fraction convergents to sqrt(488).

1, 11, 485, 5346, 235709, 2598145, 114554089, 1262693124, 55673051545, 613666260119, 27056988496781, 298240539724710, 13149640736384021, 144944288639948941, 6390698340894137425, 70442626038475460616, 3105866244033814404529

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,486,0,-1).

Formula

G.f.: -(x^2-11*x-1) / ((x^2-22*x-1)*(x^2+22*x-1)). - Colin Barker, Nov 27 2013

a(n) = 486*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 27 2013

Mathematica

Denominator[Convergents[Sqrt[488], 30]] (* Vincenzo Librandi, Dec 27 2013 *)

Prog

(Magma) I:=[1, 11, 485, 5346]; [n le 4 select I[n] else 486*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 27 2013

Crossrefs

Cf. A041930, A040465.

Sequence in context: A266026 A156863 A145516 * A322277 A101922 A263246

Adjacent sequences: A041928 A041929 A041930 * A041932 A041933 A041934

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Nov 27 2013

Status

approved