6170930domain: NAppears in sequencesa(n) = ((2^prime(n+2)-2)/prime(n+2))/3, where n >= 1.at n=7A145756Number of 2-elements orbits of S3 action on irreducible polynomials of degree 3n, n > 0, over GF(2).at n=28A165920Sets with a congruence property.at n=13A262590