login
Number of ballot sequences of length n having largest descent 2.
2

%I #5 Jun 22 2014 10:01:33

%S 1,5,21,78,292,1028,3691,13004,46452,165098,595386,2148830,7861261,

%T 28880866,107407411,401862116,1520528499,5791624015,22288596981,

%U 86362655462,337798945830,1330195410257,5283145735982,21119637660235,85089563602538,344934335418331

%N Number of ballot sequences of length n having largest descent 2.

%C Also number of ballot sequences of length n having largest ascent 2.

%Y Column k=2 of A238128 and of A238129.

%K nonn

%O 4,2

%A _Joerg Arndt_ and _Alois P. Heinz_, Jun 22 2014