Number of permutations of 2 copies of 1..n introduced in order 1..n with no element equal to another within a distance of 2.
A190823
Number of permutations of 2 copies of 1..n introduced in order 1..n with no element equal to another within a distance of 2.
Terms
- a(0) =1a(1) =0a(2) =0a(3) =1a(4) =10a(5) =99a(6) =1146a(7) =15422a(8) =237135a(9) =4106680a(10) =79154927a(11) =1681383864a(12) =39034539488a(13) =983466451011
External references
- oeis: A190823