Column 6 of table A125781.

Terms

a(0) =1a(1) =7a(2) =39a(3) =216a(4) =1274a(5) =8200a(6) =58017a(7) =451283a(8) =3847960a(9) =35818351a(10) =362337006a(11) =3965467281a(12) =46749441514a(13) =591291743032