48444505203domain: NAppears in sequencesNumber of free subsets of multiplicative group of GF(7^n).at n=12A007233a(n) = (7^n - 1)/2.at n=13A120741a(n) = floor(7^n/n).at n=13A129797A sevens sequence: a(n) = (7^n - 1)/(2^(4 - 3*(n mod 2))).at n=13A152418