4445870

Appears in sequences

• Half the number of lower triangles of a 3X3 0..n array with no element equal to the average of its horizontal and vertical neighbors.at n=13A194616
• G.f. A(x) satisfies: x = A(x) * (1 + 2*A(x)) * (1 - 3*A(x)).at n=9A250889