56404

Appears in sequences

• Number of hv-convex sets from class S having semiperimeter n of the bounding rectangle.at n=8A151828
• a(n) = 2*(a(n-1)+a(n-2)+a(n-3))-a(n-4) for n >= 4, with initial terms 0,0,1,1.at n=13A317974