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

Terms

a(0) =1a(1) =3a(2) =10a(3) =39a(4) =276a(5) =3155a(6) =46698a(7) =823599a(8) =16777288a(9) =387420579a(10) =10000000110a(11) =285311670743