%I #9 May 12 2023 15:08:06
%S 1,15,10682,163422914,39216100214432,146298576850884166522,
%T 8484183047877022205116428184,7648479804732030712438650610523878146,
%U 107185313935414834818609318544471943157967376388
%N Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.
%C Diagonal of A208408.
%H R. H. Hardin, <a href="/A208401/b208401.txt">Table of n, a(n) for n = 1..13</a>
%e Some solutions for n=4
%e ..0..1..1..2....0..0..0..1....0..1..0..0....0..1..1..0....0..0..1..0
%e ..0..1..0..0....0..1..1..0....2..0..3..0....0..0..2..0....2..0..1..2
%e ..0..0..3..0....0..1..1..0....2..0..3..1....0..2..1..1....1..3..0..0
%e ..1..1..2..0....0..0..0..1....1..2..0..2....3..1..0..0....1..3..2..2
%Y Cf. A208408.
%K nonn
%O 1,2
%A _R. H. Hardin_, Feb 26 2012
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