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

A241804

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

Terms

    a(0) =1a(1) =0a(2) =0a(3) =1a(4) =9a(5) =112a(6) =1582a(7) =26159a(8) =486170a(9) =10131071a(10) =233582056a(11) =5895589738a(12) =161776346286

External references