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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.

A207880 Number of n X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 1 and 1 1 0 vertically.

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%I A207880 #8 Jul 22 2025 20:55:16
%S A207880 2,16,82,575,4387,33631,618202,12501427,214612008,11062960730,
%T A207880 657453772615,25402400315447,3733312830860298,643896610977129232,
%U A207880 54640540348513184649,23181398334398528895458,11714931649831496203623180
%N A207880 Number of n X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 1 and 1 1 0 vertically.
%C A207880 Diagonal of A207885
%e A207880 Some solutions for n=4
%e A207880 ..1..1..0..0....0..0..1..0....1..0..0..1....0..0..1..1....0..0..1..0
%e A207880 ..1..1..0..0....0..0..1..0....0..1..0..0....0..1..1..0....1..0..0..1
%e A207880 ..1..1..1..0....1..1..1..0....1..0..0..1....0..0..1..0....0..0..1..0
%e A207880 ..1..1..0..0....0..0..1..0....0..0..1..0....0..0..1..0....1..0..0..1
%K A207880 nonn
%O A207880 1,1
%A A207880 _R. H. Hardin_ Feb 21 2012

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