Triangle, read by rows, where T(n,k) = C( n*(n+1)/2 + n-k, n-k), for n>=k>=0.

Terms

a(0) =1a(1) =2a(2) =1a(3) =10a(4) =4a(5) =1a(6) =84a(7) =28a(8) =7a(9) =1a(10) =1001a(11) =286a(12) =66a(13) =11a(14) =1a(15) =15504a(16) =3876a(17) =816a(18) =136a(19) =16a(20) =1a(21) =296010a(22) =65780a(23) =12650a(24) =2024a(25) =253a(26) =22a(27) =1a(28) =6724520a(29) =1344904