1913418

Appears in sequences

• Number of (n+2)X(1+2) 0..3 arrays with every consecutive three elements in every row and column having exactly two distinct values, and in every diagonal and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=13A252688
• Expansion of Sum_{k>=0} x^k * Product_{j=1..k} (1 + j*x^j).at n=42A306730