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

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =15a(6) =110a(7) =545a(8) =2095a(9) =6713a(10) =18750a(11) =47040a(12) =108185a(13) =231640a(14) =467034a(15) =894605a(16) =1639680a(17) =2891475a(18) =4929660a(19) =8155182a(20) =13135080a(21) =20651875a(22) =31770970a(23) =47923680a(24) =70989801a(25) =103454645a(26) =148464520a(27) =210155730a(28) =293558265a(29) =405325092