a(n) = Sum_{1 <= x_1, x_2, x_3 <= n} sigma( ( n/gcd(x_1, x_2, x_3, n) )^2 ).

Terms

a(0) =1a(1) =50a(2) =339a(3) =1786a(4) =3845a(5) =16950a(6) =19495a(7) =58682a(8) =85281a(9) =192250a(10) =176891a(11) =605454a(12) =401869a(13) =974750a(14) =1303455a(15) =1890106a(16) =1507985a(17) =4264050a(18) =2612899a(19) =6867170a(20) =6608805a(21) =8844550a(22) =6727799a(23) =19893198a(24) =12109345a(25) =20093450a(26) =20802003a(27) =34818070a(28) =21241949a(29) =65172750