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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.

A205407 Number of (n+2)X(n+2) 0..2 arrays with every 3X3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly two ways, and new values 0..2 introduced in row major order.

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%I A205407 #7 Jul 22 2025 18:50:20
%S A205407 468,44596,10331386,2839359056,2520131261396
%N A205407 Number of (n+2)X(n+2) 0..2 arrays with every 3X3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly two ways, and new values 0..2 introduced in row major order.
%C A205407 Diagonal of A205415
%e A205407 Some solutions for n=3
%e A205407 ..0..1..1..1..1....0..0..0..0..0....0..0..0..1..0....0..0..1..0..0
%e A205407 ..1..1..2..2..1....0..1..2..2..1....2..2..1..1..0....2..1..1..1..0
%e A205407 ..1..1..1..2..1....0..2..2..2..2....1..1..1..1..1....1..1..1..2..0
%e A205407 ..1..2..2..2..1....0..0..2..1..0....1..0..1..0..0....2..0..1..2..0
%e A205407 ..0..0..0..2..1....0..2..2..0..1....2..1..1..2..2....0..0..1..1..0
%K A205407 nonn
%O A205407 1,1
%A A205407 _R. H. Hardin_ Jan 26 2012

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