Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, up, down, down.
A177591
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, up, down, down.
Terms
- a(0) =1a(1) =6a(2) =90a(3) =2482a(4) =109476a(5) =7045740a(6) =623113066a(7) =72495993816
External references
- oeis: A177591