a(n) = Sum_{k=1..n^2, gcd(n,k) = 1} k.

Terms

a(0) =1a(1) =4a(2) =27a(3) =64a(4) =250a(5) =216a(6) =1029a(7) =1024a(8) =2187a(9) =2000a(10) =6655a(11) =3456a(12) =13182a(13) =8232a(14) =13500a(15) =16384a(16) =39304a(17) =17496a(18) =61731a(19) =32000a(20) =55566a(21) =53240a(22) =133837a(23) =55296a(24) =156250a(25) =105456a(26) =177147a(27) =131712a(28) =341446a(29) =108000