A041853 Denominators of continued fraction convergents to sqrt(448).

1, 6, 253, 1524, 64261, 387090, 16322041, 98319336, 4145734153, 24972724254, 1053000152821, 6342973641180, 267457893082381, 1611090332135466, 67933251842771953, 409210601388767184, 17254778510170993681, 103937881662414729270, 4382645808331589623021

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,254,0,-1).

Formula

G.f.: -(x^2 -6*x -1) / ((x^2 -16*x +1)*(x^2 +16*x +1)). - Colin Barker, Nov 26 2013

a(n) = 254*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 25 2013

Mathematica

Denominator/@Convergents[Sqrt[448], 20]  (* Harvey P. Dale, Apr 06 2011 *)

Prog

(Magma) I:=[1, 6, 253, 1524]; [n le 4 select I[n] else 254*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 25 2013

Crossrefs

Cf. A041852, A040426.

Sequence in context: A324478 A230881 A332563 * A168476 A320979 A279869

Adjacent sequences: A041850 A041851 A041852 * A041854 A041855 A041856

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Nov 26 2013

Status

approved