Hello David Seal, Very nice analysis and beautiful drawings. Thank you for the quick response. Ed Jeffery P.s.: It looks like the g.f. for row n of that array A is (Sum_{j=0..n-1} (n - j)*(-1)^Floor((j + 1)/2)*Binomial(Floor((n - j)/2) + j, j)*x^j)/(Sum_{k=0..n-1}] (-1)^Floor((k + 1)/2)*Binomial(Floor((n + k - 1)/2), k)*x^k).