A064420 Numbers n such that A064413(n+1) = n. Probably complete.

16, 26, 49, 77, 289

Offset

1,1

Comments

If A064413 begins at 2 these are the n such that A064413(n) = n.

Links

Table of n, a(n) for n=1..5.

J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG sequence, Exper. Math. 11 (2002), 437-446.

Index entries for sequences related to EKG sequence

Mathematica

nmax = 500;
ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];
EKG = Nest[ekg, {1, 2}, nmax];
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 *)

Crossrefs

Sequence in context: A347692 A204543 A155549 * A038353 A043126 A043906

Adjacent sequences: A064417 A064418 A064419 * A064421 A064422 A064423

Keyword

nonn,more

Author

Jonathan Ayres (Jonathan.ayres(AT)btinternet.com), Sep 30 2001

Extensions

No others below 10000 - Vladeta Jovovic, Oct 03 2001

No others below 10954981 - Eric M. Rains (rains(AT)caltech.edu), Oct 05, 2001.

Status

approved