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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A240643 Number of n X n 0..1 arrays with no element equal to the same number of vertical neighbors as horizontal neighbors, with new values 0..1 introduced in row major order.

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%I A240643 #7 Jul 23 2025 11:04:19
%S A240643 0,2,6,18,232,5304,227270,18030130,2764522654,770199142784
%N A240643 Number of n X n 0..1 arrays with no element equal to the same number of vertical neighbors as horizontal neighbors, with new values 0..1 introduced in row major order.
%C A240643 Diagonal of A240649
%e A240643 Some solutions for n=4
%e A240643 ..0..0..0..1....0..0..0..0....0..1..0..1....0..0..0..0....0..1..1..0
%e A240643 ..1..1..1..1....1..1..0..1....0..1..0..1....1..1..1..1....0..0..0..0
%e A240643 ..0..1..0..1....0..0..0..1....0..1..0..1....0..0..0..0....0..0..0..0
%e A240643 ..0..1..0..1....1..1..0..1....0..1..0..1....1..1..1..1....0..1..1..0
%K A240643 nonn
%O A240643 1,2
%A A240643 _R. H. Hardin_, Apr 09 2014

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