Number of permutations of length 3n with descent set {3, 6, ...} that avoid a certain pattern of length 4 or 5 (see Lewis, 2012, Appendix, for precise definition).
A217825
Number of permutations of length 3n with descent set {3, 6, ...} that avoid a certain pattern of length 4 or 5 (see Lewis, 2012, Appendix, for precise definition).
Terms
- a(0) =1a(1) =19a(2) =642a(3) =29777a(4) =1673048a(5) =106906200
External references
- oeis: A217825