Two-Catalan Triangle read by rows, for n>=0 and k>=0.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =6a(6) =6a(7) =3a(8) =1a(9) =15a(10) =36a(11) =40a(12) =29a(13) =15a(14) =5a(15) =1a(16) =91a(17) =232a(18) =280a(19) =238a(20) =154a(21) =76a(22) =28a(23) =7a(24) =1a(25) =603a(26) =1585a(27) =2025a(28) =1890a(29) =1398