Column 1 of the triangular array at A249057.

Terms

a(0) =1a(1) =4a(2) =5a(3) =24a(4) =35a(5) =192a(6) =315a(7) =1920a(8) =3465a(9) =23040a(10) =45045a(11) =322560a(12) =675675a(13) =5160960a(14) =11486475a(15) =92897280a(16) =218243025a(17) =1857945600a(18) =4583103525a(19) =40874803200a(20) =105411381075a(21) =980995276800