Number of permutations p of 1,2,...,n satisfying p(i+2) - p(i) <> 2 for all 1 <= i <= n-2.
A189281
Number of permutations p of 1,2,...,n satisfying p(i+2) - p(i) <> 2 for all 1 <= i <= n-2.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =5a(4) =18a(5) =75a(6) =410a(7) =2729a(8) =20906a(9) =181499a(10) =1763490a(11) =18943701a(12) =222822578a(13) =2847624899a(14) =39282739034a(15) =581701775369
External references
- oeis: A189281