Main diagonal sequence of triangle A073153.

Terms

a(0) =1a(1) =2a(2) =9a(3) =36a(4) =156a(5) =698a(6) =3210a(7) =15080a(8) =72060a(9) =349184a(10) =1711869a(11) =8475494a(12) =42318018a(13) =212843826a(14) =1077391794a(15) =5484472880a(16) =28058940086a(17) =144195777552a(18) =744017466318