OFFSET
1,2
COMMENTS
Numbers n such that the cyclic group Z_n is a CI-group.
The asymptotic density of this sequence is 7/Pi^2. - Amiram Eldar, May 10 2022
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
B. Alspach and M. Mishna, Enumeration of Cayley graphs and digraphs, Discr. Math., 256 (2002), 527-539.
M. Mishna, Home Page
M. Muzychuk, On Adam's conjecture for circulant graphs, Discr. Math. 167 (1997), 497-510.
MATHEMATICA
With[{upto=100}, Select[Sort[Join[{8, 9, 18}, Flatten[{#, 2#, 4#}&/@ Select[ Range[1, upto, 2], SquareFreeQ]]]], #<=upto&]] (* Harvey P. Dale, Sep 03 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 13 2006
STATUS
approved