a(n) is the smallest prime factor of 1 + lcm(1..k) where k is the n-th prime power A000961(n).

Terms

a(0) =2a(1) =3a(2) =7a(3) =13a(4) =61a(5) =421a(6) =29a(7) =2521a(8) =19a(9) =89a(10) =71a(11) =1693a(12) =232792561a(13) =6659a(14) =26771144401a(15) =331a(16) =101a(18) =1801a(19) =173a(20) =54941a(21) =89a(23) =593a(24) =5171a(25) =239a(26) =1222615931a(27) =103a(29) =6562349363a(30) =4447a(31) =147099357127a(32) =1931