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 A020446 #12 Aug 11 2025 01:21:20
%S A020446 133,157,166,181,212,253,271,283,310,334,353,394,424,466,489,491,509,
%T A020446 523,537,542,558,566,586,599,622,634,649,653,654,662,753,771,808,825,
%U A020446 826,834,849,857,873,877,926,953,972,999,1000,1004,1014,1017,1030,1033,1044,1049
%N A020446 Numbers k such that the period of the continued fraction for sqrt(k) contains exactly ten 1's.
%H A020446 Amiram Eldar, <a href="/A020446/b020446.txt">Table of n, a(n) for n = 1..10000</a>
%t A020446 cf10Q[n_]:=Module[{s=Sqrt[n]},If[IntegerQ[s],1,Count[ContinuedFraction[s][[2]],1]]==10]; Select[ Range[1200],cf10Q] (* _Harvey P. Dale_, Nov 14 2023 *)
%K A020446 nonn
%O A020446 1,1
%A A020446 _David W. Wilson_