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 A031410 #16 Aug 23 2021 15:06:49
%S A031410 51,59,67,71,79,200,232,296,320,447,519,591,723,792,856,984,1048,1112,
%T A031410 1235,1288,1315,1335,1415,1435,1535,1715,1735,1776,1835,1915,2015,
%U A031410 2064,2415,2443,2527,2616,2779,2904,3152,3227,3376,3504,3535,3563,3619,3632
%N A031410 Numbers k such that the continued fraction for sqrt(k) has even period 2*m and the m-th term of the periodic part is 7.
%H A031410 T. D. Noe, <a href="/A031410/b031410.txt">Table of n, a(n) for n = 1..1000</a>
%t A031410 n = 1; t = {}; While[Length[t] < 50, n++; If[! IntegerQ[Sqrt[n]], c = ContinuedFraction[Sqrt[n]]; len = Length[c[[2]]]; If[EvenQ[len] && c[[2, len/2]] == 7, AppendTo[t, n]]]]; t (* _T. D. Noe_, Apr 04 2014 *)
%t A031410 cf7Q[n_]:=Module[{s=Sqrt[n],cf,len},cf=If[IntegerQ[s],{1},ContinuedFraction[ s][[2]]];len = Length[cf];EvenQ[len]&&cf[[len/2]] == 7]; Select[Range[3700],cf7Q] (* _Harvey P. Dale_, Aug 23 2021 *)
%Y A031410 Cf. A031404-A031423.
%K A031410 nonn
%O A031410 1,1
%A A031410 _David W. Wilson_