A042321 Denominators of continued fraction convergents to sqrt(687).

1, 4, 5, 14, 19, 318, 337, 992, 1329, 6308, 329345, 1323688, 1653033, 4629754, 6282787, 105154346, 111437133, 328028612, 439465745, 2085891592, 108905828529, 437709205708, 546615034237, 1530939274182, 2077554308419, 34771808208886, 36849362517305

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, 330674, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1).

Formula

G.f.: -(x^18 -4*x^17 +5*x^16 -14*x^15 +19*x^14 -318*x^13 +337*x^12 -992*x^11 +1329*x^10 -6308*x^9 -1329*x^8 -992*x^7 -337*x^6 -318*x^5 -19*x^4 -14*x^3 -5*x^2 -4*x -1) / (x^20 -330674*x^10 +1). - Colin Barker, Dec 07 2013

a(n) = 330674*a(n-10) - a(n-20). - Wesley Ivan Hurt, Jun 26 2022

Mathematica

Denominator[Convergents[Sqrt[687], 30]] (* Vincenzo Librandi, Jan 20 2014 *)

Crossrefs

Cf. A042320, A040660.

Sequence in context: A300278 A129720 A041089 * A050164 A188021 A191790

Adjacent sequences: A042318 A042319 A042320 * A042322 A042323 A042324

Keyword

nonn,frac,easy

Author

N. J. A. Sloane

Extensions

More terms from Colin Barker, Dec 07 2013

Status

approved