a(n) = Sum_{k=1..n} phi(k) * (floor(n/k)^3 - floor((n-1)/k)^3).

Terms

a(0) =1a(1) =8a(2) =21a(3) =46a(4) =65a(5) =126a(6) =133a(7) =224a(8) =261a(9) =364a(10) =341a(11) =618a(12) =481a(13) =722a(14) =837a(15) =1000a(16) =833a(17) =1404a(18) =1045a(19) =1718a(20) =1641a(21) =1798a(22) =1541a(23) =2760a(24) =2065a(25) =2516a(26) =2673a(27) =3346a(28) =2465a(29) =4410