a(n) = Sum_{k=1..n-1} tau(k) * sigma_2(n-k).

Terms

a(0) =0a(1) =1a(2) =7a(3) =22a(4) =54a(5) =105a(6) =188a(7) =307a(8) =459a(9) =690a(10) =937a(11) =1307a(12) =1680a(13) =2260a(14) =2740a(15) =3588a(16) =4221a(17) =5402a(18) =6163a(19) =7714a(20) =8694a(21) =10723a(22) =11758a(23) =14449a(24) =15574a(25) =18884a(26) =20320a(27) =24228a(28) =25626a(29) =30768