OFFSET
1,7
EXAMPLE
MATHEMATICA
cnt = 0; Table[Do[If[! PrimeQ[i] && PowerMod[3, i-1, i] == 1, cnt++], {i, 2^(n-1) + 1, 2^n}]; cnt, {n, 20}] (* T. D. Noe, Mar 02 2012 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Washington Bomfim, Mar 02 2012
EXTENSIONS
a(35)-a(37) from Amiram Eldar, Jul 18 2021
STATUS
approved