A042285 Denominators of continued fraction convergents to sqrt(668).

1, 1, 6, 13, 162, 337, 1847, 2184, 111047, 113231, 677202, 1467635, 18288822, 38045279, 208515217, 246560496, 12536540017, 12783100513, 76452042582, 165687185677, 2064698270706, 4295083727089, 23540116906151, 27835200633240, 1415300148568151

Offset

0,3

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,112894,0,0,0,0,0,0,0,-1).

Formula

G.f.: -(x^14 -x^13 +6*x^12 -13*x^11 +162*x^10 -337*x^9 +1847*x^8 -2184*x^7 -1847*x^6 -337*x^5 -162*x^4 -13*x^3 -6*x^2 -x -1) / ((x^8 -336*x^4 +1)*(x^8 +336*x^4 +1)). - Colin Barker, Dec 07 2013

a(n) = 112894*a(n-8) - a(n-16). - Wesley Ivan Hurt, Mar 09 2023

Mathematica

Denominator[Convergents[Sqrt[668], 30]] (* Vincenzo Librandi, Jan 19 2014 *)

Crossrefs

Cf. A042284, A040642.

Sequence in context: A236250 A336046 A368633 * A041070 A248263 A201449

Adjacent sequences: A042282 A042283 A042284 * A042286 A042287 A042288

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Dec 07 2013

Status

approved