Search: id:A057785
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%I A057785
%S A057785 0,1,2,1,1,4,4,10,13,31,43,102
%N A057785 Blunt polypons (no 30 deg. angles) with n cells.
%C A057785 It would be nice to have a definition of "polypon"! - N. J. A. Sloane 
               (njas(AT)research.att.com), May 09 2007
%C A057785 Comments from R. J. Mathar, Dec 10 2007: (Start)
%C A057785 By looking at the Clarke pictures, I guess that the unit element is a 
               triangle with
%C A057785 internal angles of 120 degrees and two of 30 degrees. The polypons are
%C A057785 connected, nonoverlapping assemblies of these, where connectivity is 
               defined
%C A057785 via common sides; a common point is not enough. Only non-congruential
%C A057785 assemblies are counted, those which cannot be mapped onto each other 
               by
%C A057785 rotations, translations or mirrors along a line or point. However, the
%C A057785 polypons are not all of these, because some of the free-form assemblies 
               of
%C A057785 this kind would need placement of the unit that violates the format by 
               the
%C A057785 grid. (The first case where this happens is with assemblies of 3 units: 
               the
%C A057785 picture shows 2 examples with assemblies of 3 units, but I can imagine 
               at
%C A057785 least 1 more where the unit would need to hide/cover one of the grid's 
               edges.) (End)
%D A057785 Computed by Brendan Owen.
%H A057785 Andrew Clarke, <a href="http://geocities.com/alclarke0/PolyPages/PolyX/
               PolyX.htm">Other Polyforms</a>
%Y A057785 Cf. A057786.
%Y A057785 Sequence in context: A122518 A129704 A144460 this_sequence A158471 A158472 
               A118686
%Y A057785 Adjacent sequences: A057782 A057783 A057784 this_sequence A057786 A057787 
               A057788
%K A057785 nonn,nice
%O A057785 1,3
%A A057785 N. J. A. Sloane (njas(AT)research.att.com), Nov 04 2000

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