a(n) = Sum_{i=1..n, gcd(i,n)=1} i*phi(i) where phi is Euler's totient function A000010.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =17a(5) =21a(6) =49a(7) =69a(8) =105a(9) =103a(10) =217a(11) =173a(12) =375a(13) =347a(14) =435a(15) =509a(16) =863a(17) =601a(18) =1243a(19) =983a(20) =1271a(21) =1265a(22) =2217a(23) =1449a(24) =2575a(25) =2225a(26) =2935a(27) =2573a(28) =4549a(29) =2241