327791domain: NAppears in sequencesComposite numbers whose prime factors contain no digits other than 1 and 8.at n=21A036308Number of -1..1 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having one, two or three distinct values for every i<=n and j<=n.at n=12A211478