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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.

A207215 Number of n X n 0..2 arrays avoiding the pattern z z+1 z in any row or column.

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%I A207215 #8 Jul 22 2025 20:08:15
%S A207215 3,81,12534,12584703,86510224720,4019515127529418,
%T A207215 1256433426475190769775,2643803004141585682944365943
%N A207215 Number of n X n 0..2 arrays avoiding the pattern z z+1 z in any row or column.
%C A207215 Diagonal of A207221
%e A207215 Some solutions for n=4
%e A207215 ..2..0..2..1....2..1..0..2....2..0..0..0....2..0..1..1....0..2..0..1
%e A207215 ..1..1..1..0....1..1..1..2....0..1..1..0....2..1..0..1....2..0..1..1
%e A207215 ..0..1..2..2....1..1..2..2....0..1..1..2....1..2..2..2....0..2..1..1
%e A207215 ..0..0..0..2....1..1..0..1....2..2..0..1....1..0..0..0....2..0..0..1
%K A207215 nonn
%O A207215 1,1
%A A207215 _R. H. Hardin_ Feb 16 2012

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