Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).
A217807
Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).
Terms
- a(0) =1a(1) =4a(2) =29a(3) =292a(4) =3620a(5) =51866a(6) =827415a(7) =14350467a(8) =266218320
External references
- oeis: A217807