139500domain: NAppears in sequencesG.f. satisfies: 13*A(x) = 12 + 27*x + A(x)^4, starting with [1,3,6].at n=7A120595Binomial transform of A120070.at n=13A141595Numbers k such that k and uphi(k) have the same set of prime divisors, where uphi is the unitary totient function (A047994).at n=39A329859