A031819 - OEIS

%I #10 Jan 19 2014 09:56:36

%S 13939,28531,40891,50059,52264,55183,58927,65656,66887,73051,82519,

%T 94824,108539,111896,113263,114955,119743,131723,131811,133867,147823,

%U 155803,158299,161155,162819,163283,169336,169663,169675,176623,180671,187039

%N Period of continued fraction for sqrt(n) contains exactly 51 ones.

%t cf51Q[n_]:=Module[{sr=Sqrt[n],x},x=If[IntegerQ[sr],1,Count[ ContinuedFraction[ sr][[2]],1]];x==51]; Select[Range[200000],cf51Q] (* _Harvey P. Dale_, Jan 19 2014 *)

%K nonn

%O 1,1

%A _David W. Wilson_