187736domain: NAppears in sequencesNumbers n such that phi(n) = sigma(n) - sigma(n+1).at n=7A063943Number of (n+1) X (3+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=19A258549