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

Terms

a(0) =1a(1) =1a(2) =5a(3) =10a(4) =30a(5) =26a(6) =91a(7) =84a(8) =159a(9) =140a(10) =385a(11) =196a(12) =650a(13) =406a(14) =620a(15) =680a(16) =1496a(17) =654a(18) =2109a(19) =1080a(20) =1806a(21) =1650a(22) =3795a(23) =1544a(24) =4150a(25) =2756a(26) =4365a(27) =3164a(28) =7714a(29) =2360