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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.

A209520 Number of n X n 0..7 arrays with every 2X2 subblock containing exactly one value repeat, and new values 0..7 introduced in row major order.

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%I A209520 #8 Jul 22 2025 21:47:20
%S A209520 1,6,2027,27323948,16484968944748,258381047085271692456
%N A209520 Number of n X n 0..7 arrays with every 2X2 subblock containing exactly one value repeat, and new values 0..7 introduced in row major order.
%C A209520 Diagonal of A209527
%e A209520 Some solutions for n=5
%e A209520 ..0..0..0..0..0....0..0..0..0..0....0..0..0..1..0....0..0..0..0..1
%e A209520 ..1..2..1..2..1....1..2..1..2..3....1..2..3..0..2....1..2..1..3..3
%e A209520 ..2..3..2..0..0....1..3..3..1..2....0..0..2..0..1....2..0..0..0..1
%e A209520 ..1..1..1..1..2....4..4..5..1..4....4..1..0..1..2....1..1..2..1..2
%e A209520 ..0..2..0..2..0....5..6..6..5..1....1..2..0..2..0....0..2..0..0..0
%K A209520 nonn
%O A209520 1,2
%A A209520 _R. H. Hardin_ Mar 10 2012

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