Number of permutations p of [n] such that p(i)-i is a multiple of eight for all i in [n].

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =1a(8) =1a(9) =2a(10) =4a(11) =8a(12) =16a(13) =32a(14) =64a(15) =128a(16) =256a(17) =768a(18) =2304a(19) =6912a(20) =20736a(21) =62208a(22) =186624a(23) =559872a(24) =1679616a(25) =6718464a(26) =26873856a(27) =107495424a(28) =429981696a(29) =1719926784