%I #14 Aug 17 2021 23:48:27
%S 2502,2514,2518,2542,2546,2558,2566,2578,2582,2594,2606,2614,2638,
%T 2654,2658,2662,2686,2694,2702,5628,5637,5673,5691,5694,5721,5793,
%U 5799,5817,5844,5853,5871,5889,5937,5961,5979,5982,5988,5997,6009,6033,6081,10004
%N that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 50.
%H Harvey P. Dale, <a href="/A031548/b031548.txt">Table of n, a(n) for n = 1..1000</a>
%t ct50Q[n_]:=Module[{s=Sqrt[n],cf,len},cf=If[IntegerQ[s],{0}, ContinuedFraction[ s][[2]]];len=Length[cf];EvenQ[len]&& cf[[len/2]] == 50]; Select[Range[11000],ct50Q] (* _Harvey P. Dale_, May 10 2015 *)
%K nonn
%O 1,1
%A _David W. Wilson_
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