-335813478000domain: ZAppears in sequencesa(n) = Sum_{k = 0..n-1} (-1)^k*binomial(n,k)*binomial(n-1,k)^2.at n=19A361710a(1) = 1 and a(n) = Sum_{k = 0..n-2} (-1)^k * binomial(n,k)^2 * binomial(n-2,k) for n >= 2.at n=18A361711a(n) = Sum_{k = 0..n-1} (-1)^k*binomial(n,k)^2*binomial(n-1,k).at n=19A361716