The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {2,3,4,5} for all i from 1 to n-1.
A174705
The number of permutations p of {1,...,n} such that |p(i)-p(i+1)| is in {2,3,4,5} for all i from 1 to n-1.
Terms
- a(0) =1a(1) =0a(2) =0a(3) =2a(4) =14a(5) =90a(6) =462a(7) =1668a(8) =4496a(9) =11332a(10) =31718a(11) =100258a(12) =336142a(13) =1123212a(14) =3614554a(15) =11128872a(16) =33226646a(17) =98298782a(18) =292626532a(19) =879380718a(20) =2654884024a(21) =8000680668a(22) =23965094526a(23) =71287278676a(24) =210922844362a(25) =622218231406
External references
- oeis: A174705