Number of permutations of {0,1,...,2n} with first element n whose sequence of ascents and descents forms a Dyck path.

A316727

Number of permutations of {0,1,...,2n} with first element n whose sequence of ascents and descents forms a Dyck path.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =87a(4) =3337a(5) =223333a(6) =23068057a(7) =3403720071a(8) =679894572497

External references