%I #23 Sep 08 2022 08:44:53
%S 1,2,5,62,129,320,3969,8258,20485,254078,528641,1311360,16264961,
%T 33841282,83947525,1041211582,2166370689,5373952960,66653806209,
%U 138681565378,344016936965,4266884808958,8877786554881,22022457918720,273147281579521,568317021077762
%N Denominators of continued fraction convergents to sqrt(41).
%H Vincenzo Librandi, <a href="/A041069/b041069.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 (0,0,64,0,0,1).
%F G.f.: -(x^4-2*x^3+5*x^2+2*x+1) / (x^6+64*x^3-1). - _Colin Barker_, Nov 12 2013
%F a(n) = 64*a(n-3) + a(n-6). - _Vincenzo Librandi_, Dec 10 2013
%t Table[Denominator[FromContinuedFraction[ContinuedFraction[Sqrt[41], n]]], {n, 1, 50}] (* _Vladimir Joseph Stephan Orlovsky_, Mar 21 2011 *)
%t Denominator[Convergents[Sqrt[41], 30]] (* _Vincenzo Librandi_, Dec 10 2013 *)
%t LinearRecurrence[{0,0,64,0,0,1},{1,2,5,62,129,320},40] (* _Harvey P. Dale_, Jun 19 2022 *)
%o (Magma) I:=[1, 2, 5, 62, 129, 320]; [n le 6 select I[n] else 64*Self(n-3)+Self(n-6): n in [1..30]]; // _Vincenzo Librandi_, Dec 10 2013
%Y Cf. A010495, A041068.
%K nonn,cofr,frac,easy
%O 0,2
%A _N. J. A. Sloane_.
%E More terms from _Colin Barker_, Nov 12 2013