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%I #34 Jul 19 2015 09:02:52
%S 1,2,14,126,1267,13550,150665
%N Number of distinct connected planar figures that can be formed from 1 X 2 rectangles (or dominoes) such that each pair of touching rectangles shares exactly one edge, of length 1.
%C Figures that differ by a rotation or reflection are regarded as distinct (cf. A216583).
%C This sequence is A216581 without the condition that the adjacency graph of the dominoes forms a tree.
%C An example: The two solutions
%C V H -
%C | V
%C H - |
%C and
%C H - V
%C V |
%C | H -
%C are considered to be the same because the resulting shape is the same.
%H César E. Lozada, <a href="/A216583/a216583.pdf">Illustration of terms n <= 4 of A216583</a>
%H Manfred Scheucher, <a href="/A216595/a216595.py.txt">Python Script</a>
%H N. J. A. Sloane, <a href="/A056786/a056786.jpg">Illustration of initial terms of A056786, A216598, A216583, A216595, A216492, A216581</a> (Exclude figures marked (A))
%H N. J. A. Sloane, <a href="/A056786/a056786.pdf">Illustration of third term of A056786, A216598, A216583, A216595, A216492, A216581</a> (a better drawing for the third term)
%H M. Vicher, <a href="http://www.vicher.cz/puzzle/polyforms.htm">Polyforms</a>
%H <a href="/index/Do#domino">Index entries for sequences related to dominoes</a>
%Y Cf. A056786, A216598, A216583, A216595, A216492, A216581.
%K nonn,more
%O 0,2
%A _N. J. A. Sloane_, Sep 08 2012
%E Terms a(4)-a(6) added by _César Eliud Lozada_, Sep 09 2012
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