Number of nX3 arrays containing 3 indistinguishable copies of 1..n with rows and columns in lexicographically strictly increasing order.
A180837
Number of nX3 arrays containing 3 indistinguishable copies of 1..n with rows and columns in lexicographically strictly increasing order.
Terms
- a(0) =1a(1) =1a(2) =77a(3) =5385a(4) =545426a(5) =79230924a(6) =15755497776
External references
- oeis: A180837