a(n) = Product_{d|n, d^2<=n} (d+n/d); a(1)=1.

Terms

a(0) =1a(1) =3a(2) =4a(3) =20a(4) =6a(5) =35a(6) =8a(7) =54a(8) =60a(9) =77a(10) =12a(11) =728a(12) =14a(13) =135a(14) =128a(15) =1360a(16) =18a(17) =1881a(18) =20a(19) =2268a(20) =220a(21) =299a(22) =24a(23) =38500a(24) =260a(25) =405a(26) =336a(27) =5104a(28) =30a(29) =75361