3221504

Appears in sequences

• Triangle T(n,k), n>=0, 0<=k<=C(n,2), read by rows: T(n,k) = number of k-length chains in the poset of Dyck paths of semilength n ordered by inclusion.at n=40A193629
• a(n) = n*(n-1)*(n- 2)^2*2^(n-4)/3.at n=12A391778