A convolution triangle of numbers based on A027307.

Terms

a(0) =1a(1) =2a(2) =1a(3) =10a(4) =4a(5) =1a(6) =66a(7) =24a(8) =6a(9) =1a(10) =498a(11) =172a(12) =42a(13) =8a(14) =1a(15) =4066a(16) =1360a(17) =326a(18) =64a(19) =10a(20) =1a(21) =34970a(22) =11444a(23) =2706a(24) =536a(25) =90a(26) =12a(27) =1a(28) =312066a(29) =100520