a(n) = Product_{1<=x<=n, n|(x^2-1)} x.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =105a(8) =8a(9) =9a(10) =10a(11) =385a(12) =12a(13) =13a(14) =616a(15) =945a(16) =16a(17) =17a(18) =18a(19) =1881a(20) =2080a(21) =21a(22) =22a(23) =37182145a(24) =24a(25) =25a(26) =26a(27) =5265a(28) =28a(29) =6061