The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {1,2,3} for all i from 1 to n-1.
A174700
The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {1,2,3} for all i from 1 to n-1.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =72a(6) =180a(7) =428a(8) =1042a(9) =2512a(10) =5912a(11) =13592a(12) =30872a(13) =69560a(14) =155568a(15) =345282a(16) =761312a(17) =1669612a(18) =3645236a(19) =7927404a(20) =17180092a(21) =37119040a(22) =79986902a(23) =171964534a(24) =368959906a(25) =790214816a(26) =1689779842a(27) =3608413750a(28) =7696189046a(29) =16397254612
External references
- oeis: A174700