Triangular array read by rows: T(n, k) is the number of n X 2 Young tableaux with k vertical walls.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =6a(5) =6a(6) =5a(7) =20a(8) =30a(9) =20a(10) =14a(11) =70a(12) =140a(13) =140a(14) =70a(15) =42a(16) =252a(17) =630a(18) =840a(19) =630a(20) =252a(21) =132a(22) =924a(23) =2772a(24) =4620a(25) =4620a(26) =2772a(27) =924a(28) =429a(29) =3432