a(n) is the least positive number whose divisors have all possible residues mod n.

Terms

a(0) =1a(1) =2a(2) =6a(3) =12a(4) =40a(5) =30a(6) =84a(7) =120a(8) =288a(9) =270a(10) =990a(11) =420a(12) =936a(13) =1638a(14) =840a(15) =2160a(16) =5100a(17) =4410a(18) =8208a(19) =5940a(20) =3360a(21) =6930a(22) =12420a(23) =10920a(24) =14400a(25) =19890a(26) =28080a(27) =27300a(28) =48720a(29) =43890