Number of permutations p of [n] such that p(i) > p(i+1) iff i == 1 (mod 9).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =5a(7) =6a(8) =7a(9) =8a(10) =9a(11) =89a(12) =583a(13) =2562a(14) =8996a(15) =27013a(16) =72057a(17) =175016a(18) =393805a(19) =831384a(20) =14964895a(21) =171416216a(22) =1274511567a(23) =7351608748a(24) =35319494255a(25) =147208687584a(26) =546836589610