OFFSET
1,2
COMMENTS
Contains A127102 as a subsequence.
From M. F. Hasler, Nov 21 2018: (Start)
The first terms not in A127102 are a({10, 11, 14, 20, 21, 22, ...}) = {188097287, 233727361, 1515836567, 13162910047, 24088984969, 29683374847, ...}.
The listed terms are all squarefree, and all but the first two terms appear to be divisible by either a(3) = 7*127 or a(4) = 7*337. Are there exceptions to these properties? (End)
MATHEMATICA
Select[Range[2 10^5], IntegerQ[(8^(#^2) - 1) / #^3] &] (* or *) Select[Range[2 10^6], IntegerQ[(PowerMod[8, #, #^2] - 1) / #^3] &] (* Vincenzo Librandi, Nov 23 2018 *)
PROG
(PARI) is(n)=Mod(8, n^3)^n^2==1 \\ M. F. Hasler, Nov 21 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Max Alekseyev, May 17 2010
EXTENSIONS
a(23)-a(26) from Giovanni Resta, Nov 23 2018
STATUS
approved