A042221 Denominators of continued fraction convergents to sqrt(636).

1, 4, 5, 9, 32, 105, 1292, 3981, 13235, 17216, 30451, 139020, 6981451, 28064824, 35046275, 63111099, 224379572, 736249815, 9059377352, 27914381871, 92802522965, 120716904836, 213519427801, 974794616040, 48953250229801, 196787795535244

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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7011902, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1).

Formula

a(n) = 7011902*a(n-12) - a(n-24) for n>23. - Vincenzo Librandi, Jan 17 2014

Mathematica

Denominator[Convergents[Sqrt[636], 30]] (* Harvey P. Dale, Jan 28 2013 *)

Crossrefs

Cf. A042220.

Sequence in context: A336661 A352509 A222543 * A341252 A041151 A279919

Adjacent sequences: A042218 A042219 A042220 * A042222 A042223 A042224

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Vincenzo Librandi, Jan 17 2014

Status

approved