2208840domain: NAppears in sequencesNumber of (n+1) X (2+1) 0..4 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 2, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).at n=8A234915Numbers n such that sigma(n) = m*sigma(n+2) with some m > 1.at n=18A260988