Number of nX2 arrays containing 2 indistinguishable copies of 1..n with lexicographical ordering of rows strictly increasing and columns strictly decreasing.

A180840

Number of nX2 arrays containing 2 indistinguishable copies of 1..n with lexicographical ordering of rows strictly increasing and columns strictly decreasing.

Terms

    a(0) =1a(1) =0a(2) =2a(3) =17a(4) =131a(5) =1220a(6) =13796a(7) =183095a(8) =2790353a(9) =48045596a(10) =922507880a(11) =19543670381a(12) =452869998215

External references