%I A006762 M3534
%S A006762 0,0,4,17,61,214,758,2723,9908,36444,135266,505859,1903888,7204872,27394664,
               104592935,400795842
%N A006762 Number of fixed polyominoes with n cells.
%C A006762 This sequence counts only polyominoes that are strictly 2-dimensional 
               - it excludes those where all the squares are in a single line. Thus 
               for n>1, a(n) = A001168(n) - 2. - Franklin T. Adams-Watters, Jul 
               29 2007
%D A006762 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006762 W. F. Lunnon, Counting multidimensional polyominoes. Computer Journal 
               18 (1975), no. 4, pp. 366-367.
%Y A006762 Cf. A001168.
%Y A006762 Sequence in context: A027075 A034331 A107278 this_sequence A122231 A119916 
               A005784
%Y A006762 Adjacent sequences: A006759 A006760 A006761 this_sequence A006763 A006764 
               A006765
%K A006762 nonn
%O A006762 1,3
%A A006762 N. J. A. Sloane (njas(AT)research.att.com).