OFFSET
1,1
COMMENTS
The odd terms are "anti-Carmichael pseudoprimes (3,2)" defined as follows: numbers k > 1 such that 3^k == 3 (mod k) and gcd(k, 2^k-2) = 1. Cf. A300762 (2,3).
We impose k>2, since we want these to be pseudoprimes, thus composite numbers.
MATHEMATICA
Select[Range[3, 2*10^6], PowerMod[3, #-1, #] == 1 && GCD[#, #-1 + PowerMod[2, #-1, #]] == 1 &] (* Giovanni Resta, Aug 18 2018 *)
PROG
(PARI) isok(k) = (k>2) && (Mod(3, k)^(k-1) == Mod(1, k)) && (gcd(k, 2^(k-1)-1) == 1); \\ Michel Marcus, Aug 18 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Thomas Ordowski, Aug 18 2018
EXTENSIONS
More terms from Michel Marcus, Aug 18 2018
Further terms from Giovanni Resta, Aug 18 2018
STATUS
approved