%I A006773 M3959
%S A006773 1,5,30,186,1164,7344,46732,299604,1932900,12537542,81705782,534663812,
%T A006773 3511466838,23136724382,152888000934,1012925595468,6726766841438,44767880394634
%N A006773 Sum of squared spans of n-step polygons on square lattice.
%D A006773 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006773 A. J. Guttmann and I. G. Enting, The size and number of rings on the 
               square lattice, J. Phys. A 21 (1988), L165-L172.
%Y A006773 Sequence in context: A147837 A076036 A161407 this_sequence A059273 A038744 
               A098663
%Y A006773 Adjacent sequences: A006770 A006771 A006772 this_sequence A006774 A006775 
               A006776
%K A006773 nonn
%O A006773 1,2
%A A006773 N. J. A. Sloane (njas(AT)research.att.com).