Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).
A217809
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) =462a(4) =6070a(5) =90686a(6) =1493962a(7) =26584610a(8) =503663959
External references
- oeis: A217809