387420507domain: NAppears in sequencesDirichlet convolution of 3^(n-1) with phi(n).at n=18A034754a(n) = 3^n + n.at n=18A104743Numbers that can be represented as both x^y + y and b^c + b + c, for some b, c, x, y > 1.at n=5A253916a(n) = Sum_{d|n} phi(n/d) * (-3)^(d-1).at n=18A383000