a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 18.

A161213

a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 18.

Terms

    a(0) =1a(1) =131071a(2) =64570081a(3) =8589869056a(4) =190734863281

External references