A diagonal of A059438.

Terms

a(0) =1a(1) =3a(2) =12a(3) =58a(4) =327a(5) =2109a(6) =15366a(7) =125316a(8) =1135329a(9) =11348623a(10) =124359336a(11) =1484796894a(12) =19204214363a(13) =267627706257