a(n) = A013928(A002110(n)).

Terms

a(0) =0a(1) =1a(2) =4a(3) =18a(4) =128a(5) =1404a(6) =18261a(7) =310346a(8) =5896727a(9) =135624239a(10) =3933101823a(11) =121926157640