a(n) = Sum_{k=1..n-1} k^2*sigma(k)*sigma(n-k).

Terms

a(0) =0a(1) =1a(2) =15a(3) =76a(4) =275a(5) =720a(6) =1666a(7) =3440a(8) =6129a(9) =11250a(10) =17545a(11) =28896a(12) =41405a(13) =65072a(14) =85950a(15) =128960a(16) =162996a(17) =238545a(18) =286995a(19) =404600a(20) =482160a(21) =662112a(22) =756470a(23) =1042560a(24) =1150625a(25) =1549730a(26) =1732590a(27) =2257920a(28) =2443105a(29) =3250800