A041239 - OEIS

%I #13 Jun 13 2015 00:49:23

%S 1,2,9,101,413,927,20807,42541,190971,2143222,8763859,19670940,

%T 441524539,902720018,4052404611,45479170739,185969087567,417417345873,

%U 9369150696773,19155718739419,85992025654449

%N Denominators of continued fraction convergents to sqrt(131).

%H Vincenzo Librandi, <a href="/A041239/b041239.txt">Table of n, a(n) for n = 0..200</a>

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,21220,0,0,0,0,0,-1).

%F a(n) = 21220*a(n-6)-a(n-12). G.f.: -(x^10-2*x^9+9*x^8-101*x^7+413*x^6-927*x^5-413*x^4-101*x^3-9*x^2-2*x-1)/(x^12-21220*x^6+1). [_Colin Barker_, Jul 19 2012]

%t Denominator[Convergents[Sqrt[131], 30]] (* _Vincenzo Librandi_, Oct 24 2013 *)

%Y Cf. A041238.

%K nonn,cofr,frac,easy

%O 0,2

%A _N. J. A. Sloane_.