Least prime of the form x^n-x-1.

Terms

a(0) =5a(1) =5a(2) =13a(3) =29a(4) =61a(5) =2097143a(6) =1679609a(7) =509a(8) =1021a(9) =8589934583a(10) =4093a(11) =67108859a(12) =16381a(13) =470184984569a(14) =4294967291a(16) =68719476731a(18) =1048573a(19) =10460353199a(20) =4194301a(22) =16777213a(27) =536870909