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

Terms

a(0) =1a(1) =8a(2) =27a(3) =70a(4) =125a(5) =216a(6) =343a(7) =578a(8) =753a(9) =1000a(10) =1331a(11) =1890a(12) =2197a(13) =2744a(14) =3375a(15) =4666a(16) =4913a(17) =6024a(18) =6859a(19) =8750a(20) =9261a(21) =10648a(22) =12167a(23) =15606a(24) =15745a(25) =17576a(26) =20427a(27) =24010a(28) =24389a(29) =27000