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

Terms

a(0) =1a(1) =1a(2) =1a(3) =6a(4) =3a(5) =1a(6) =56a(7) =21a(8) =6a(9) =1a(10) =715a(11) =220a(12) =55a(13) =10a(14) =1a(15) =11628a(16) =3060a(17) =680a(18) =120a(19) =15a(20) =1a(21) =230230a(22) =53130a(23) =10626a(24) =1771a(25) =231a(26) =21a(27) =1a(28) =5379616a(29) =1107568