387422001domain: NAppears in sequencesa(n) = Sum_{d|9} phi(d)*n^(9/d).at n=9A054608a(n) = Sum_{d|n} phi(d)*9^(n/d).at n=9A054616Triangle T(n,k) = Sum_{d|n} phi(d)*k^(n/d).at n=44A054618Triangle T(n,k) = Sum_{d|k} phi(d)*n^(k/d).at n=44A054619a(n) = Sum_{d|n} phi(d)*n^(n/d).at n=9A228640a(n) = -Sum_{d|n} phi(n/d) * (-n)^d.at n=8A382997