%I #13 Feb 13 2019 08:01:53
%S 16,26,49,77,289
%N Numbers n such that A064413(n+1) = n. Probably complete.
%C If A064413 begins at 2 these are the n such that A064413(n) = n.
%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 = 500;
%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 For[n = 1, n <= nmax, n++, If[EKG[[n+1]] == n, Print[n]]] (* _Jean-François Alcover_, Feb 13 2019, after _Robert G. Wilson v_ in A064413 *)
%K nonn,more
%O 1,1
%A Jonathan Ayres (Jonathan.ayres(AT)btinternet.com), Sep 30 2001
%E No others below 10000 - _Vladeta Jovovic_, Oct 03 2001
%E No others below 10954981 - Eric M. Rains (rains(AT)caltech.edu), Oct 05, 2001.