Largest prime factor of n! + 2^n - 1.

Terms

a(0) =2a(1) =5a(2) =13a(3) =13a(4) =151a(5) =29a(6) =5167a(7) =541a(8) =51913a(9) =691a(10) =39918847a(11) =1520653a(12) =9631a(13) =2748457a(14) =171793a(15) =37698720637a(16) =429056005099a(17) =10201231a(19) =26573a(22) =522781919969a(26) =4561301027