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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The formula given simplifies to 2^(2*n*(n-1))-1. - Alexander M Kerr, Feb 10 2012

LINKS

Table of n, a(n) for n=1..9.

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: A153832 A198524 A208463 * A139297 A211251 A208469

Adjacent sequences:  A172319 A172320 A172321 * A172323 A172324 A172325

KEYWORD

nonn

AUTHOR

Alexander M Kerr, Jan 31 2010

STATUS

approved

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Last modified April 23 03:26 EDT 2019. Contains 322380 sequences. (Running on oeis4.)