Number of permutations p of [n] such that p(i) > p(i+1) iff i == 0 (mod 10).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =1a(8) =1a(9) =1a(10) =1a(11) =10a(12) =65a(13) =285a(14) =1000a(15) =3002a(16) =8007a(17) =19447a(18) =43757a(19) =92377a(20) =184755a(21) =3527140a(22) =42031760a(23) =326057040a(24) =1961245375a(25) =9812764391a(26) =42530831916a(27) =164059546366a(28) =574224816166