A042321 - OEIS

%I #18 Jun 26 2022 02:43:24

%S 1,4,5,14,19,318,337,992,1329,6308,329345,1323688,1653033,4629754,

%T 6282787,105154346,111437133,328028612,439465745,2085891592,

%U 108905828529,437709205708,546615034237,1530939274182,2077554308419,34771808208886,36849362517305

%N Denominators of continued fraction convergents to sqrt(687).

%H Vincenzo Librandi, <a href="/A042321/b042321.txt">Table of n, a(n) for n = 0..200</a>

%H <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 330674, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1).

%F 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

%F a(n) = 330674*a(n-10) - a(n-20). - _Wesley Ivan Hurt_, Jun 26 2022

%t Denominator[Convergents[Sqrt[687], 30]] (* _Vincenzo Librandi_, Jan 20 2014 *)

%Y Cf. A042320, A040660.

%K nonn,frac,easy

%O 0,2

%A _N. J. A. Sloane_

%E More terms from _Colin Barker_, Dec 07 2013