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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.

A204684 Number of nX7 0..3 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..3 introduced in row major order.

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%I A204684 #7 Jul 22 2025 18:14:06
%S A204684 528,6427791,24932875448,115180678788869,517329649988490420
%N A204684 Number of nX7 0..3 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..3 introduced in row major order.
%C A204684 Column 7 of A204685
%e A204684 Some solutions for n=5
%e A204684 ..0..1..1..0..0..2..3....0..0..1..0..0..1..1....0..0..1..0..1..1..0
%e A204684 ..3..0..0..2..1..3..2....2..1..0..1..3..1..3....0..2..1..2..3..3..0
%e A204684 ..0..1..1..2..0..1..2....3..1..1..3..0..2..0....3..2..2..0..1..2..3
%e A204684 ..1..3..0..0..1..3..3....0..2..0..0..1..1..3....2..0..1..3..1..1..2
%e A204684 ..2..0..2..2..1..1..0....3..0..3..1..1..3..2....0..2..1..3..3..1..2
%K A204684 nonn
%O A204684 1,1
%A A204684 _R. H. Hardin_ Jan 18 2012

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