A172322 Number of graphs with nonzero edge sets on an n X n square grid for n=(1,2,3,...).

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

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