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A172322
Number of graphs with nonzero edge sets on an n X n square grid for n=(1,2,3,...).
0
0, 15, 4095, 16777215, 1099511627775, 1152921504606846975, 19342813113834066795298815, 5192296858534827628530496329220095, 22300745198530623141535718272648361505980415
OFFSET
1,2
COMMENTS
The formula given simplifies to 2^(2*n*(n-1))-1. - Alexander M Kerr, Feb 10 2012
FORMULA
a(n) = Sum_{i=1..2*(n^2-n)} binomial(2*(n^2-n),i), n >= 1.
EXAMPLE
For n=1, a(1)=0 since a minimum of a 2 X 2 grid is required to have edges.
MATHEMATICA
Total[Table[Binomial[2(n^2-n), i], {i, 2(n^2-n)}]]
CROSSREFS
Sequence in context: A208463 A374796 A374335 * A139297 A211251 A208469
KEYWORD
nonn
AUTHOR
Alexander M Kerr, Jan 31 2010
STATUS
approved