Number of permutations p of [n] such that p(i) > p(i+1) iff i == 0 (mod 7).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =1a(8) =7a(9) =35a(10) =119a(11) =329a(12) =791a(13) =1715a(14) =3431a(15) =45031a(16) =400281a(17) =2313633a(18) =10467037a(19) =39845281a(20) =132908041a(21) =398840401a(22) =7677528495a(23) =98103087719a(24) =800524248391