This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A031617 #18 Aug 18 2021 00:10:32
%S A031617 5501,10453,17770,18037,26365,27017,36269,49066,63793,76537,81017,
%T A031617 112754,114773,116129,132394,133121,134581,135314,136049,136786,
%U A031617 138266,139009,139754,140501,154393,159133,180617,185741,187465,203461,204362
%N A031617 Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 29.
%t A031617 opct29Q[n_]:=Module[{cf=ContinuedFraction[Sqrt[n]][[2]],len}, len= Length[ cf]; OddQ[len]&&cf[[Floor[len/2]]]==29]; Select[Range[205000], !IntegerQ[Sqrt[#]]&&opct29Q[#]&] (* _Harvey P. Dale_, Dec 14 2011 *)
%Y A031617 Subsequence of A003814.
%K A031617 nonn
%O A031617 1,1
%A A031617 _David W. Wilson_
%E A031617 Corrected by _Harvey P. Dale_, Dec 14 2011