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 A010337 #16 Aug 21 2025 08:30:17
%S A010337 13,29,53,74,85,89,125,173,185,218,229,293,338,346,365,373,445,533,
%T A010337 557,629,701,733,818,845,914,925,965,985,1009,1042,1093,1105,1129,
%U A010337 1145,1229,1373,1378,1490,1525,1685,1853,1901,1970,2029,2138,2213,2362,2378,2405
%N A010337 Numbers k such that the continued fraction for sqrt(k) has period 5.
%H A010337 Amiram Eldar, <a href="/A010337/b010337.txt">Table of n, a(n) for n = 1..10000</a>
%t A010337 q[k_] := Module[{c = ContinuedFraction[Sqrt[k]]}, Length[c] == 2 && Length[c[[2]]] == 5]; Select[Range[2500], q] (* _Amiram Eldar_, Aug 21 2025 *)
%K A010337 nonn
%O A010337 1,1
%A A010337 _N. J. A. Sloane_ and Walter Gilbert