Number of n-celled polyominoes, where the cells are 1 X 2 rectangles with some of the edges of length 2 replaced by curved arcs that either sag inwards or bulge outwards.

A056755

Number of n-celled polyominoes, where the cells are 1 X 2 rectangles with some of the edges of length 2 replaced by curved arcs that either sag inwards or bulge outwards.