Triangle read by rows: T(n,k) number of tilings of a 2n X 3 grid by dominoes, 2k of which are in a vertical position (0<=k<=n).

A123519

Triangle read by rows: T(n,k) number of tilings of a 2n X 3 grid by dominoes, 2k of which are in a vertical position (0<=k<=n).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =1a(4) =6a(5) =4a(6) =1a(7) =12a(8) =20a(9) =8a(10) =1a(11) =20a(12) =60a(13) =56a(14) =16a(15) =1a(16) =30a(17) =140a(18) =224a(19) =144a(20) =32a(21) =1a(22) =42a(23) =280a(24) =672a(25) =720a(26) =352a(27) =64a(28) =1a(29) =56

External references