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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.

A204972 Number of n X n 0..2 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..2 introduced in row major order.

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%I A204972 #9 Jul 22 2025 18:28:42
%S A204972 1,14,1217,451468,594430765,2924321664147
%N A204972 Number of n X n 0..2 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..2 introduced in row major order.
%C A204972 Diagonal of A204978
%e A204972 Some solutions for n=5
%e A204972 ..0..1..2..0..1....0..1..2..0..1....0..0..1..0..1....0..1..1..2..2
%e A204972 ..2..1..2..2..0....2..2..1..1..2....2..1..2..1..2....1..1..2..1..1
%e A204972 ..0..0..1..2..0....1..2..2..0..1....2..1..2..1..2....0..0..1..2..2
%e A204972 ..0..1..0..0..1....0..0..1..1..2....0..2..1..2..0....2..0..0..2..0
%e A204972 ..2..2..1..2..1....2..2..0..2..1....1..2..0..2..0....2..2..1..1..2
%K A204972 nonn
%O A204972 1,2
%A A204972 _R. H. Hardin_ Jan 21 2012

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