189506domain: NAppears in sequencesa(n) = Sum_{k=1..n-1} gcd(k,n)*a(k), a(1) = 1.at n=16A072979Number of (7+1) X (n+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.at n=28A258560