a(n) = n^n + n*n + n+n + 1.

Terms

a(0) =2a(1) =5a(2) =13a(3) =43a(4) =281a(5) =3161a(6) =46705a(7) =823607a(8) =16777297a(9) =387420589a(10) =10000000121a(11) =285311670755