Number of permutations p of [n] such that p(i) > p(i+1) iff i == 1 (mod 8).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =5a(7) =6a(8) =7a(9) =8a(10) =71a(11) =430a(12) =1749a(13) =5708a(14) =16003a(15) =40026a(16) =91505a(17) =194464a(18) =3111409a(19) =32514338a(20) =220345299a(21) =1161515620a(22) =5117035637a(23) =19624019910a(24) =67294308247a(25) =210311057024