Sixth column of triangle A067323.

Terms

a(0) =42a(1) =174a(2) =645a(3) =2333a(4) =8398a(5) =30275a(6) =109550a(7) =398180a(8) =1453908a(9) =5332407a(10) =19639521a(11) =72616727a(12) =269473750a(13) =1003347975a(14) =3747412770a(15) =14036374680a(16) =52714429260a(17) =198459284400a(18) =748867149234