210862080

Appears in sequences

• Number of walks of length n on square lattice, starting at origin, staying on points with x+y >= 0.at n=15A060899
• a(n) = (3*0^n + 4^n*binomial(2*n,n))/4.at n=8A099045
• a(n) = 2^n*n!/((floor(n/2)+1)*floor(n/2)!^2).at n=15A240558