3355615450

Appears in sequences

• a(n) = (binomial(4*n, 2*n) + (-1)^n*binomial(2*n, n)^2)/2.at n=9A036911
• a(n) = 1/2*binomial(2*n,n) - (1+(-1)^n)/4*(binomial(n,floor(n/2)))^2.at n=18A058621
• a(n) = Sum_{k=0..n-1} binomial(2*n, k)^2.at n=9A387635