498037

Appears in sequences

• Number of n X n binary matrices, symmetric under 90-degree rotation, with no more than 2 ones in any 2 X 2 subblock.at n=10A141507
• a(n) = Sum_{k=0..floor(n/2)} (binomial(n,k) * binomial(n-k,k))^2.at n=8A382841