Number of permutations of [2n] avoiding the pattern 12...n.

A269042

Number of permutations of [2n] avoiding the pattern 12...n.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =132a(4) =15767a(5) =2190688a(6) =370531683a(7) =77182248916

External references