cp's OEIS Frontend

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.

%I A121194 #10 Nov 06 2013 10:45:43
%S A121194 1,2,10,84
%N 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.
%C A121194 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.
%C A121194 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.
%C A121194 See the Applegate link for further information.
%H A121194 David Applegate, <a href="/A121194/a121194.txt">Explanation of rules; examples; differences from A056755</a>
%H A121194 M. Vicher, <a href="http://www.vicher.cz/puzzle/polyforms.htm">Polyforms</a>
%H A121194 M. Vicher, <a href="http://www.vicher.cz/puzzle/polyform/new1/images/b1.gif">The 10 2-celled polyominoes mentioned in A056755</a>
%H A121194 M. Vicher, <a href="/A056755/a056755a.gif">The 10 2-celled polyominoes mentioned in A056755</a> [Taken from the Vicher web site]
%H A121194 M. Vicher, <a href="http://www.vicher.cz/puzzle/polyform/new1/images/p6.gif">The 68 3-celled polyominoes mentioned in A056755</a>
%H A121194 M. Vicher, <a href="/A056755/a056755b.gif">The 68 3-celled polyominoes mentioned in A056755</a> [Taken from the Vicher web site]
%Y A121194 Cf. A056755, A056786.
%K A121194 nice,nonn,more
%O A121194 0,2
%A A121194 _David Applegate_