Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).
A217808
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) =5a(2) =42a(3) =453a(4) =5651a(5) =77498a(6) =1135828a(7) =17485309a(8) =279540684
External references
- oeis: A217808