Number of nX2 arrays containing 2 indistinguishable copies of 1..n with rows and columns in lexicographically strictly increasing order.
A180836
Number of nX2 arrays containing 2 indistinguishable copies of 1..n with rows and columns in lexicographically strictly increasing order.
Terms
- a(0) =1a(1) =1a(2) =9a(3) =72a(4) =678a(5) =7719a(6) =102963a(7) =1573764a(8) =27143466a(9) =521698683a(10) =11059018599a(11) =256349691978
External references
- oeis: A180836