a(n) = Sum_{k=1..n-1} k^7 * sigma(k) * sigma(n-k).

Terms

a(0) =0a(1) =1a(2) =387a(3) =9904a(4) =142475a(5) =850500a(6) =5287786a(7) =19400960a(8) =68736681a(9) =210682950a(10) =565317445a(11) =1328193216a(12) =3163440917a(13) =6945663368a(14) =13045807350a(15) =26914795520a(16) =48673795956a(17) =89900901837a(18) =149363037975a(19) =262436871200a(20) =409003474320a(21) =711715515852