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 A064473 #8 Feb 07 2019 12:04:37
%S A064473 4,5,9,10,13,14,19,20,21,23,24,27,28,32,33,36,37,38,42,43,49,50,52,53,
%T A064473 56,57,60,61,66,67,68,73,74,75,77,80,81,83,84,88,89,92,95,96,99,100,
%U A064473 106,107,108,110,111,114,115,117,118,123,124,127,128
%N A064473 Where the odd terms appear in A064413 (if it begins at 2).
%H A064473 J. C. Lagarias, E. M. Rains and N. J. A. Sloane, <a href="http://arXiv.org/abs/math.NT/0204011">The EKG sequence</a>, Exper. Math. 11 (2002), 437-446.
%H A064473 <a href="/index/Ed#EKG">Index entries for sequences related to EKG sequence</a>
%t A064473 ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];
%t A064473 EKG = Nest[ekg, {1, 2}, 200] // Rest;
%t A064473 Position[EKG, _?OddQ] // Flatten (* _Jean-François Alcover_, Feb 07 2019, after _Robert G. Wilson v_ in A064413 *)
%Y A064473 Cf. A064413. See A064957 for better version.
%K A064473 nonn
%O A064473 1,1
%A A064473 _N. J. A. Sloane_, Oct 05 2001