Number of permutations p of {1..2n} such that p[2k-1]<p[2k] <=> p[2k]<p[2k+1].
A261683
Number of permutations p of {1..2n} such that p[2k-1]<p[2k] <=> p[2k]<p[2k+1].
Terms
- a(0) =2a(1) =8a(2) =84a(3) =1632a(4) =51040a(5) =2340480a(6) =147985824a(7) =12338740736
External references
- oeis: A261683