%I #7 Jan 22 2014 10:43:26
%S 64051,75799,76639,85783,129299,132487,146467,148264,151859,162131,
%T 162511,192131,214927,223343,224779,224899,250931,251395,262456,
%U 273607,289931,292811,316611,318491,331255,343864,345043,346019,347459,353995
%N Period of continued fraction for sqrt(n) contains exactly 91 ones.
%t cf91Q[n_]:=Module[{sr=Sqrt[n],p},p=If[IntegerQ[sr],1,Count[ ContinuedFraction[ sr][[2]],1]];p==91]; Select[Range[400000],cf91Q] (* _Harvey P. Dale_, Jan 22 2014 *)
%K nonn
%O 1,1
%A _David W. Wilson_