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).
A217822
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) =9a(2) =153a(3) =3465a(4) =92169a(5) =2716425
External references
- oeis: A217822