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).
A217828
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) =1134a(3) =114621a(4) =15952918a(5) =2763262475
External references
- oeis: A217828