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

Terms

a(0) =1a(1) =14a(2) =72a(3) =271a(4) =731a(5) =1649a(6) =3417a(7) =6654a(8) =11495a(9) =18635a(10) =29971a(11) =45088a(12) =67562a(13) =95862a(14) =129315a(15) =180548a(16) =247178a(17) =324463a(18) =429785a(19) =547025a(20) =679318a(21) =853788a(22) =1080248a(23) =1324791a(24) =1617620a(25) =1964622a(26) =2361036a(27) =2813206a(28) =3392778a(29) =3946537