a(n) is the largest prime factor of n^n - n.

Terms

a(0) =2a(1) =3a(2) =7a(3) =13a(4) =311a(5) =43a(6) =337a(7) =193a(8) =333667a(9) =13421a(10) =266981089a(11) =28393a(12) =29914249171a(13) =10678711a(14) =1321a(15) =184417a(17) =236377a(18) =192696104561a(19) =920421641a(23) =152587500001a(25) =797161