1679600

Appears in sequences

• Expansion of (1-4*x)^(19/2).at n=23A020931
• a(n) = n * binomial(2*n, n-1).at n=10A110609
• Number of valleys in all left factors of Dyck paths of length n. A valley is a (1,-1)-step followed by a (1,1)-step.at n=21A191522