A020386 - OEIS

%I #16 Sep 27 2024 20:03:04

%S 1069,1993,2801,2969,3589,3865,4241,4289,4337,4618,5981,6089,6109,

%T 6173,6833,7457,8629,9194,11909,12113,14666,15353,15973,16066,17002,

%U 17009,19450,19858,21346,21722,24370,25189,26485,26861,29597,30269,30986,31090

%N Numbers k such that the continued fraction for sqrt(k) has period 47.

%t cf47Q[n_]:=Module[{s=Sqrt[n]},If[IntegerQ[s],1,Length[ContinuedFraction[s][[2]]]]==47];Select[Range[32000],cf47Q] (* _Harvey P. Dale_, Sep 27 2024 *)

%Y Cf. A003285.

%K nonn

%O 1,1

%A _David W. Wilson_