a(n) = Sum_{k=1..n} phi(n*k).

Terms

a(0) =1a(1) =3a(2) =10a(3) =18a(4) =44a(5) =40a(6) =114a(7) =124a(8) =198a(9) =192a(10) =430a(11) =292a(12) =708a(13) =540a(14) =704a(15) =888a(16) =1552a(17) =954a(18) =2178a(19) =1456a(20) =1980a(21) =2080a(22) =3806a(23) =2216a(24) =4220a(25) =3480a(26) =4734a(27) =4056a(28) =7588a(29) =3560