3-Springer numbers.

Terms

a(0) =1a(1) =1a(2) =3a(3) =16a(4) =88a(5) =625a(6) =5527a(7) =55760a(8) =640540a(9) =8329326a(10) =120212331a(11) =1905939913a(12) =32987637967a(13) =618591571085