565249domain: NAppears in sequencesa(n) = 3*Catalan(n) - Catalan(n-1) - 1.at n=11A000781Number of n X 3 0..1 arrays with every element equal to 1, 2 or 4 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.at n=10A302273a(n) = Sum_{k=0..n} binomial(4*n+1,k) * binomial(4*n-k,n-k).at n=5A383716