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 A206584 #8 Oct 05 2022 13:32:39
%S A206584 2,5,52,329,379,639,631,3937,1471,2461,2524,6931,3259,11809,5659,
%T A206584 16756,8779,14749,10399,24721,14452,25429,16669,31021,16879,45301,
%U A206584 21061,45109,31054,72721,28414,81061,40189,86041,34654,109909,44371,74881,42046,79501,53551
%N A206584 The least number s having exactly n fours in the continued fraction of sqrt(s).
%t A206584 nn = 50; zeros = nn; t = Table[0, {nn}]; k = 2; While[zeros > 0, If[! IntegerQ[Sqrt[k]], cnt = Count[ContinuedFraction[Sqrt[k]][[2]], 4]; If[cnt <= nn && t[[cnt]] == 0, t[[cnt]] = k; zeros--]]; k++]; Join[{2}, t]
%t A206584 With[{tbl=Table[{n,Count[If[IntegerQ[Sqrt[n]],{1},ContinuedFraction[Sqrt[n]][[2]]],4]},{n,2,110000}]},Table[SelectFirst[tbl,#[[2]]==k&],{k,0,40}]][[All,1]] (* _Harvey P. Dale_, Oct 05 2022 *)
%Y A206584 Cf. A206578 (n ones), A206582 (n twos), A206583 (n threes), A206585 (n fives).
%K A206584 nonn
%O A206584 0,1
%A A206584 _T. D. Noe_, Mar 19 2012