a(1) = 1, a(n) = least prime divisor of b(n), where b(1) = 1, b(n) = n*b(n-1) + 1 = A002627(n).

Terms

a(0) =1a(1) =3a(2) =2a(3) =41a(4) =2a(5) =1237a(6) =2a(7) =29a(8) =2a(9) =43a(10) =2a(11) =5a(12) =2a(13) =5a(14) =2a(16) =2a(17) =28001a(18) =2a(19) =1409a(20) =2a(21) =5a(22) =2a(23) =5a(24) =2a(25) =47a(26) =2a(27) =661a(28) =2a(29) =13a(30) =2