%I #23 Dec 27 2023 00:32:54
%S 20,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,
%T 5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,
%U 40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40,5,40
%N Continued fraction for sqrt(408).
%H <a href="/index/Con#confC">Index entries for continued fractions for constants</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F a(n) = 5*(9+7*(-1)^n)/2 for n>0. a(n) = a(n-2) for n>2. G.f.: -5*(4*x^2+x+4) / ((x-1)*(x+1)). [_Colin Barker_, Mar 25 2013]
%p with(numtheory): Digits := 300: convert(evalf(sqrt(408)),confrac);
%t Block[{$MaxExtraPrecision=1000}, ContinuedFraction[Sqrt[408],100]]
%t (* or *)
%t PadRight[{20},100,{40,5}] (* _Harvey P. Dale_, Oct 06 2020 *)
%K nonn,cofr,easy
%O 0,1
%A _N. J. A. Sloane_.