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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.

A203174 Number of n X n 0..2 arrays with every 1 immediately preceded by 0 to the left or above, no 0 immediately preceded by a 0, and every 2 immediately preceded by 0 1 to the left or above.

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%I A203174 #8 Jul 22 2025 17:02:34
%S A203174 1,1,7,59,952,32411,2208945,323885934,84492757788,47354744651060,
%T A203174 53683376052551785,116641756206417848067,528882406558326590368278
%N A203174 Number of n X n 0..2 arrays with every 1 immediately preceded by 0 to the left or above, no 0 immediately preceded by a 0, and every 2 immediately preceded by 0 1 to the left or above.
%C A203174 Diagonal of A203181
%e A203174 Some solutions for n=5
%e A203174 ..0..1..0..1..2....0..1..0..1..2....0..1..0..1..2....0..1..2..0..1
%e A203174 ..1..0..1..2..0....1..0..1..0..1....1..0..1..0..1....1..0..1..2..0
%e A203174 ..0..1..0..1..1....2..1..2..1..0....2..1..2..1..0....0..1..2..0..1
%e A203174 ..1..0..1..0..2....0..2..0..1..1....0..1..0..2..1....1..0..1..1..0
%e A203174 ..0..1..0..1..2....1..0..1..0..2....1..0..1..2..2....0..1..0..1..2
%K A203174 nonn
%O A203174 1,3
%A A203174 _R. H. Hardin_ Dec 30 2011

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