279978domain: NAppears in sequencesSums of 3 distinct powers of 6.at n=37A038479Numbers k such that 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=21A099411a(n) = n^7 + 7*n.at n=6A180357a(n) = 6^n + 6*n.at n=7A221908