%I #18 Dec 26 2023 06:39:06
%S 20,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,
%T 1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,
%U 19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19,1,40,1,19
%N Continued fraction for sqrt(439).
%H <a href="/index/Con#confC">Index entries for continued fractions for constants</a>.
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,1).
%F From _Amiram Eldar_, Dec 26 2023: (Start)
%F Multiplicative with a(2) = 19, a(2^e) = 40 for e >= 2, and a(p^e) = 1 for an odd prime p.
%F Dirichlet g.f.: zeta(s) * (1 + 9/2^(s-1) + 21/2^(2*s)). (End)
%p with(numtheory): Digits := 300: convert(evalf(sqrt(439)),confrac);
%t ContinuedFraction[Sqrt[439],120] (* or *) PadRight[{20},120,{40,1,19,1}] (* _Harvey P. Dale_, Jun 24 2018 *)
%K nonn,cofr,easy,mult
%O 0,1
%A _N. J. A. Sloane_