Triangle: row #n has n+1 terms. T(n,m) = 4^m (2n+1)! / ( (2n-2m)! (2m+1)! ).

Terms

a(0) =1a(1) =3a(2) =4a(3) =5a(4) =40a(5) =16a(6) =7a(7) =140a(8) =336a(9) =64a(10) =9a(11) =336a(12) =2016a(13) =2304a(14) =256a(15) =11a(16) =660a(17) =7392a(18) =21120a(19) =14080a(20) =1024a(21) =13a(22) =1144a(23) =20592a(24) =109824a(25) =183040a(26) =79872a(27) =4096a(28) =15a(29) =1820