a(n) = Sum_{k=0..n} A047848(k, n-k).

Terms

a(0) =1a(1) =3a(2) =8a(3) =23a(4) =73a(5) =251a(6) =920a(7) =3573a(8) =14695a(9) =64047a(10) =295792a(11) =1445659a(12) =7460349a(13) =40539363a(14) =231303192a(15) =1381924345a(16) =8623569739a(17) =56078184471a(18) =379232618512