|
%I #12 Jul 10 2021 19:35:54
%S 181,277,394,397,409,433,641,809,953,1217,1277,1489,1637,1861,2089,
%T 2146,2257,2314,2393,2425,2693,2762,2825,3098,3425,3977,3989,4777,
%U 5165,5237,5669,5785,6122,6610,7045,7306,7673,7717,7738,7946,8146,8938,9010,9250
%N Numbers k such that the continued fraction for sqrt(k) has period 21.
%t cf21Q[n_]:=Module[{s=Sqrt[n]},If[IntegerQ[s],1,Length[ ContinuedFraction[ s][[2]]]]==21]; Select[Range[10000],cf21Q] (* _Harvey P. Dale_, Sep 22 2019 *)
%K nonn
%O 1,1
%A _David W. Wilson_
|
