a(n) = n / gcd(n, (n-1)!).

Terms

a(0) =1a(1) =2a(2) =3a(3) =2a(4) =5a(5) =1a(6) =7a(7) =1a(8) =1a(9) =1a(10) =11a(11) =1a(12) =13a(13) =1a(14) =1a(15) =1a(16) =17a(17) =1a(18) =19a(19) =1a(20) =1a(21) =1a(22) =23a(23) =1a(24) =1a(25) =1a(26) =1a(27) =1a(28) =29a(29) =1