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%I #12 Aug 10 2015 00:30:37
%S 0,15,4095,16777215,1099511627775,1152921504606846975,
%T 19342813113834066795298815,5192296858534827628530496329220095,
%U 22300745198530623141535718272648361505980415
%N Number of graphs with nonzero edge sets on an n X n square grid for n=(1,2,3,...).
%C The formula given simplifies to 2^(2*n*(n-1))-1. - _Alexander M Kerr_, Feb 10 2012
%F a(n) = Sum_{i=1..2*(n^2-n)} binomial(2*(n^2-n),i), n >= 1.
%e For n=1, a(1)=0 since a minimum of a 2 X 2 grid is required to have edges.
%t Total[Table[Binomial[2(n^2-n), i], {i, 2(n^2-n)}]]
%K nonn
%O 1,2
%A _Alexander M Kerr_, Jan 31 2010
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