a(n) = n^n - n + 1.A006091a(n) = n^n - n + 1.Terms a(0) =1a(1) =3a(2) =25a(3) =253a(4) =3121a(5) =46651a(6) =823537a(7) =16777209a(8) =387420481a(9) =9999999991a(10) =285311670601External referencesoeis: A006091