1809025

Appears in sequences

• Number of n X 3 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 0 1 1 vertically.at n=27A207118
• a(n) = Sum_{k=0..n} C(2*k, k)^2 * C(n+k, n-k).at n=6A243945
• Number of (n+1)X(3+1) arrays of permutations of 0..n*4+3 with each element having directed index change -1,0 0,2 -1,-2 or 1,0.at n=11A264515