A convolution triangle of numbers obtained from A025748.

Terms

a(0) =1a(1) =3a(2) =1a(3) =15a(4) =6a(5) =1a(6) =90a(7) =39a(8) =9a(9) =1a(10) =594a(11) =270a(12) =72a(13) =12a(14) =1a(15) =4158a(16) =1953a(17) =567a(18) =114a(19) =15a(20) =1a(21) =30294a(22) =14580a(23) =4482a(24) =1008a(25) =165a(26) =18a(27) =1a(28) =227205a(29) =111456