A093149 a(1) = 4; a(n) = (n^(n+1)+2*n-3)/(n-1) for n >= 2.

4, 9, 42, 343, 3908, 55989, 960802, 19173963, 435848052, 11111111113, 313842837674, 9726655034463, 328114698808276, 11966776581370173, 469172025408063618, 19676527011956855059, 878942778254232811940, 41660902667961039785745, 2088331858752553232964202