Number of ballot sequences of length 2n+1 having exactly n descents.

A241805

Number of ballot sequences of length 2n+1 having exactly n descents.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =17a(4) =146a(5) =1615a(6) =21895a(7) =349021a(8) =6385041a(9) =131722015a(10) =3019039806a(11) =76052414727

External references