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A121194
Number of n-celled polyominoes, where the cells are 1 X 2 rectangles with one edge of length 2 replaced by a curved arc that either sags inwards or bulges outwards, subject to some restrictions.
3
OFFSET
0,2
COMMENTS
This is the result of trying to infer the rules behind A056755. The match is not exact - these rules allow 16 3-celled polyominoes not allowed in A056755. However, the reason for the exclusion of those 16 polyominoes in A056755 is not clear.
The restrictions are: all curved edges must be on the boundary of the polyomino, each side of the polyomino must be either all curved, or all straight and if two cells meet on a side of length 2, they must share the whole side. Polyominoes are allowed to be rotated and reflected.
See the Applegate link for further information.
CROSSREFS
Sequence in context: A050390 A298690 A101878 * A302572 A121516 A024491
KEYWORD
nice,nonn,more
STATUS
approved