OFFSET
1,1
COMMENTS
Computed terms are prime.
MATHEMATICA
Select[Range[3, 10^7, 2], PowerMod[7, (# - 1)/2, (t = #*(# - 1)/2)] == t - 1 &] (* Amiram Eldar, Sep 24 2020 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Benoit Cloitre, Sep 24 2020
EXTENSIONS
a(9)-a(12) from Amiram Eldar, Sep 25 2020
STATUS
approved