a(1) = 2, a(n+1) is smallest prime factor of (2 * Product_{k=1..n} a(k)) + 1.

Terms

a(0) =2a(1) =5a(2) =3a(3) =61a(4) =7a(5) =25621a(6) =656410021a(7) =8874301a(8) =9137a(9) =1069a(10) =491a(11) =23a(12) =1031a(13) =17a(14) =19a(15) =41a(16) =197a(17) =311a(18) =1187a(19) =113a(20) =11a(21) =1249a(23) =13a(24) =43a(25) =89a(26) =239a(27) =56359a(28) =31732153a(29) =29a(30) =37