a(n) = Sum_{d|n} phi(d)^2.

Terms

a(0) =1a(1) =2a(2) =5a(3) =6a(4) =17a(5) =10a(6) =37a(7) =22a(8) =41a(9) =34a(10) =101a(11) =30a(12) =145a(13) =74a(14) =85a(15) =86a(16) =257a(17) =82a(18) =325a(19) =102a(20) =185a(21) =202a(22) =485a(23) =110a(24) =417a(25) =290a(26) =365a(27) =222a(28) =785a(29) =170