The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {1,2,3,4} for all i from 1 to n-1.
A174701
The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {1,2,3,4} for all i from 1 to n-1.
Terms
- a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =480a(6) =1632a(7) =5124a(8) =15860a(9) =50186a(10) =158808a(11) =496472a(12) =1526736a(13) =4627392a(14) =13908192a(15) =41570256a(16) =123658616a(17) =366072856a(18) =1078360714a(19) =3162222448a(20) =9236396440a(21) =26885780412a(22) =78022705424a(23) =225793573676a(24) =651761629560
External references
- oeis: A174701