%I #8 Feb 13 2019 08:02:07
%S 1,2,3,6,4,5,9,7,12,8,10,11,15,14,13,18,16,17,21,19,20,22,23,24,25,26,
%T 27,28,30,35,29,33,31,36,32,34,37,39,38,40,41,42,44,43,45,50,46,47,48,
%U 49,52,51,54,53,57,55,56,58,59,60,65,61,63,70,62,64
%N The even subsequence of A064413, divided by 2.
%H 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 <a href="/index/Ed#EKG">Index entries for sequences related to EKG sequence</a>
%t nmax = 120;
%t ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];
%t EKG = Nest[ekg, {1, 2}, nmax];
%t Select[EKG, EvenQ]/2 (* _Jean-François Alcover_, Feb 13 2019, after _Robert G. Wilson v_ in A064413 *)
%Y Cf. A064413.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Oct 05 2001