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 A031414 #25 Aug 19 2021 23:26:18
%S A031414 13,29,53,58,74,85,97,106,125,137,157,173,185,229,233,241,293,298,314,
%T A031414 338,346,353,365,389,397,425,433,445,457,461,533,538,541,554,557,593,
%U A031414 629,634,641,661,673,698,733,746,754,769,794,818,821,829,845,857,877
%N A031414 Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 1.
%H A031414 T. D. Noe, <a href="/A031414/b031414.txt">Table of n, a(n) for n = 1..1000</a>
%e A031414 The continued fraction of sqrt[29] is {5; 2, 1, 1, 2, 10}. The center number in the periodic part is 1.
%t A031414 n = 1; t = {}; While[Length[t] < 60, n++; If[! IntegerQ[Sqrt[n]], c = ContinuedFraction[Sqrt[n]]; len = Length[c[[2]]]; If[OddQ[len] && c[[2, (len + 1)/2]] == 1, AppendTo[t, n]]]]; t (* _T. D. Noe_, Apr 03 2014 *)
%Y A031414 Cf. A031404-A031423.
%Y A031414 Subsequence of A003814.
%K A031414 nonn
%O A031414 1,1
%A A031414 _David W. Wilson_
%E A031414 Initial 2 removed by _T. D. Noe_, Apr 03 2014
%E A031414 Definitions of A031414-A031423 clarified by _N. J. A. Sloane_, Aug 18 2021