A031859 - OEIS

%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_