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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.

A181218 Number of n X n binary matrices with no three 1's adjacent in a line horizontally, vertically, diagonally or antidiagonally.

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%I A181218 #5 Jul 22 2025 08:36:27
%S A181218 2,16,230,10732,1495392,507962194,493466099722,1328921689649459,
%T A181218 9633695407844528952,192630734231370260714836,
%U A181218 10572973250296811381776668634
%N A181218 Number of n X n binary matrices with no three 1's adjacent in a line horizontally, vertically, diagonally or antidiagonally.
%C A181218 Diagonal of A181224
%e A181218 Some avoided solutions for 3X3
%e A181218 ..1..1..1....1..0..0....0..0..1....1..1..1....1..0..0....1..1..0....1..0..0
%e A181218 ..0..0..0....0..1..1....0..1..0....0..0..1....0..0..0....0..1..0....1..0..0
%e A181218 ..0..0..1....0..0..1....1..0..1....0..0..0....1..1..1....0..0..1....1..1..0
%K A181218 nonn
%O A181218 1,1
%A A181218 _R. H. Hardin_ Oct 10 2010

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