Triangle T(n,k) = binomial(n+2,k+1)*(binomial(n+2,k+1)-1), n >=0, 0 <= k <= n.

Terms

a(0) =2a(1) =6a(2) =6a(3) =12a(4) =30a(5) =12a(6) =20a(7) =90a(8) =90a(9) =20a(10) =30a(11) =210a(12) =380a(13) =210a(14) =30a(15) =42a(16) =420a(17) =1190a(18) =1190a(19) =420a(20) =42a(21) =56a(22) =756a(23) =3080a(24) =4830a(25) =3080a(26) =756a(27) =56a(28) =72a(29) =1260