Sum_{d=1..n} phi(d)*mu(d).

Terms

a(0) =0a(1) =1a(2) =0a(3) =-2a(4) =-2a(5) =-6a(6) =-4a(7) =-10a(8) =-10a(9) =-10a(10) =-6a(11) =-16a(12) =-16a(13) =-28a(14) =-22a(15) =-14a(16) =-14a(17) =-30a(18) =-30a(19) =-48a(20) =-48a(21) =-36a(22) =-26a(23) =-48a(24) =-48a(25) =-48a(26) =-36a(27) =-36a(28) =-36a(29) =-64