Number of permutations p of [n] such that for each i in [n] we have: (i>1) and |p(i)-p(i-1)| = 1 or (i<n) and |p(i)-p(i+1)| = 1.
A363181
Number of permutations p of [n] such that for each i in [n] we have: (i>1) and |p(i)-p(i-1)| = 1 or (i<n) and |p(i)-p(i+1)| = 1.
Terms
- a(0) =1a(1) =0a(2) =2a(3) =2a(4) =8a(5) =14a(6) =54a(7) =128a(8) =498a(9) =1426a(10) =5736a(11) =18814a(12) =78886a(13) =287296a(14) =1258018a(15) =4986402a(16) =22789000a(17) =96966318a(18) =461790998a(19) =2088374592a(20) =10343408786a(21) =49343711666a(22) =253644381032
External references
- oeis: A363181