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

Terms

a(0) =1a(1) =22a(2) =105a(3) =394a(4) =745a(5) =2310a(6) =2737a(7) =6490a(8) =8817a(9) =16390a(10) =15961a(11) =41370a(12) =30745a(13) =60214a(14) =78225a(15) =104602a(16) =88417a(17) =193974a(18) =137161a(19) =293530a(20) =287385a(21) =351142a(22) =291985a(23) =681450a(24) =469345a(25) =676390a(26) =717081a(27) =1078378a(28) =731641a(29) =1720950