1,1

This is the result of trying to infer the rules behind A056755. The match is not exact - these rules allow 16 3-cell 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.

David Applegate, Explanation of rules; examples; differences from A056755

M. Vicher, Polyforms

M. Vicher, The 10 2-celled polyominoes mentioned in A056755

M. Vicher, The 10 2-celled polyominoes mentioned in A056755 [Taken from the Vicher web site]

M. Vicher, The 68 3-celled polyominoes mentioned in A056755

M. Vicher, The 68 3-celled polyominoes mentioned in A056755 [Taken from the Vicher web site]

Cf. A056755, A056786.

Adjacent sequences: A121191 A121192 A121193 this_sequence A121195 A121196 A121197

Sequence in context: A006679 A050390 A101878 this_sequence A121516 A024491 A113332

nice,nonn,more,bref

David Applegate (david(AT)research.att.com)