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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.

A202881 Number of n X n 0..2 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor.

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%I A202881 #9 Jul 19 2023 09:40:47
%S A202881 1,35,5493,6092872,56006562037,4095290003129296,
%T A202881 2365289879500027706428,10827985400073310953152590562,
%U A202881 392915439811314078675718437985175633,112991429416970014192131075985467073204579858
%N A202881 Number of n X n 0..2 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor.
%e A202881 Some solutions for n=3
%e A202881 ..1..2..2....0..1..1....0..2..1....2..1..2....2..2..0....2..2..1....0..1..0
%e A202881 ..1..1..1....0..2..0....1..2..2....2..2..2....2..2..1....2..1..0....1..2..0
%e A202881 ..0..1..0....1..2..2....1..1..0....2..2..1....0..0..1....0..1..1....1..2..1
%Y A202881 Diagonal of A202889.
%K A202881 nonn,more
%O A202881 1,2
%A A202881 _R. H. Hardin_, Dec 25 2011

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