Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, up.
A177639
Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, up.
Terms
- a(0) =1a(1) =46a(2) =11722a(3) =9659528a(4) =19879855515
External references
- oeis: A177639