Largest prime factor of n! - 1.

Terms

a(0) =1a(1) =5a(2) =23a(3) =17a(4) =719a(5) =5039a(6) =1753a(7) =2999a(8) =125131a(9) =7853a(10) =479001599a(11) =3593203a(12) =87178291199a(13) =1510259a(14) =6880233439a(15) =256443711677a(16) =478749547a(17) =78143369a(20) =170006681813a(22) =991459181683