%I A006770 M3565
%S A006770 1,4,20,110,638,3832,23592,147941,940982,6053180,39299408,257105146,
%T A006770 1692931066,11208974860,74570549714,498174818986,3340366308393
%N A006770 Number of fixed n-celled polyominoes which need only touch at corners.
%C A006770 Also known as fixed polyplets [From David Bevan (dbevan(AT)emtex.com), 
               Jul 28 2009]
%D A006770 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006770 D. H. Redelmeier, personal communication.
%H A006770 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Polyplet.html">Link to a section of The World of Mathematics.</a>
%e A006770 a(2)=4: the two fixed dominoes and the two rotations of the polyplet 
               consisting of two cells touching at a vertex [From David Bevan (dbevan(AT)emtex.com), 
               Jul 28 2009]
%Y A006770 Cf. A030222 (free polyplets) [From David Bevan (dbevan(AT)emtex.com), 
               Jul 28 2009]
%Y A006770 Sequence in context: A020084 A026127 A153295 this_sequence A158827 A026156 
               A025183
%Y A006770 Adjacent sequences: A006767 A006768 A006769 this_sequence A006771 A006772 
               A006773
%K A006770 nonn,hard
%O A006770 1,2
%A A006770 N. J. A. Sloane (njas(AT)research.att.com).
%E A006770 One more term from Joseph Myers (jsm(AT)polyomino.org.uk), Sep 26 2002