Smallest prime factor of 4*n! - 1.

Terms

a(0) =3a(1) =3a(2) =7a(3) =23a(4) =5a(5) =479a(6) =2879a(7) =19a(8) =17a(9) =569a(10) =14515199a(11) =159667199a(12) =73a(13) =47a(14) =61a(15) =4993a(16) =43a(17) =455999a(18) =409a(19) =1562713a(20) =1249a(21) =59a(22) =50207a(23) =29a(24) =71a(25) =61651424911a(26) =1407512357a(27) =41a(28) =43613a(29) =10839629