Number of permutations p of 1,2,...,n satisfying |p(i+4)-p(i)|<>4 for all 1<=i<=n-4.
A189255
Number of permutations p of 1,2,...,n satisfying |p(i+4)-p(i)|<>4 for all 1<=i<=n-4.
Terms
- a(0) =1a(1) =2a(2) =6a(3) =24a(4) =108a(5) =544a(6) =3264a(7) =23040a(8) =176832a(9) =1563392a(10) =15536160a(11) =171172224a(12) =2066033472a(13) =27146652480a(14) =385447394880
External references
- oeis: A189255