A020393 - OEIS

%I #14 Jul 11 2021 01:19:37

%S 886,1747,1821,2361,2404,2662,2899,2998,3097,3307,3412,3796,3907,4061,

%T 4166,4246,4377,4459,4724,4769,4819,4866,4911,5044,5079,5147,5171,

%U 5299,5531,5561,5574,5599,5665,5860,5889,5987,6011,6059,6190,6262,6265,6323

%N Numbers k such that the continued fraction for sqrt(k) has period 54.

%t cf54Q[n_]:=Module[{s=Sqrt[n]},If[IntegerQ[s],1,Length[ ContinuedFraction[ s][[2]]]]==54]; Select[Range[6400],cf54Q] (* _Harvey P. Dale_, Mar 24 2017 *)

%Y Cf. A003285.

%K nonn

%O 1,1

%A _David W. Wilson_