A convolution triangle of numbers obtained from A034171.

Terms

a(0) =1a(1) =6a(2) =1a(3) =42a(4) =12a(5) =1a(6) =315a(7) =120a(8) =18a(9) =1a(10) =2457a(11) =1134a(12) =234a(13) =24a(14) =1a(15) =19656a(16) =10458a(17) =2673a(18) =384a(19) =30a(20) =1a(21) =160056a(22) =95256a(23) =28539a(24) =5148a(25) =570a(26) =36a(27) =1a(28) =1320462a(29) =861597