Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, up, up.
A177568
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, up, up.
Terms
- a(0) =1a(1) =6a(2) =89a(3) =2412a(4) =103370a(5) =6437048a(6) =549450394a(7) =61608807138
External references
- oeis: A177568