a(n) = Sum_{i+j+k+l+m+r=n, i,j,k,l,m,r >= 1} sigma(i)*sigma(j)*sigma(k)*sigma(l)*sigma(m)*sigma(r).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =18a(7) =159a(8) =942a(9) =4281a(10) =16050a(11) =51932a(12) =149532a(13) =391524a(14) =947246a(15) =2143677a(16) =4581204a(17) =9316195a(18) =18138636a(19) =33984912a(20) =61534652a(21) =108055425a(22) =184582014a(23) =307515038a(24) =500798058a(25) =798762453a(26) =1249917936a(27) =1921788036a(28) =2907159804a(29) =4332046200