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A215900 Number of diagonal and antidiagonal neighbor colorings of the even squares of an nX3 array with new integer colors introduced in row major order.

%I A215900 #6 Jul 22 2025 23:27:08
%S A215900 2,2,15,42,726,2906,84550,433252,18378580,113503692,6485270720,
%T A215900 46538017584,3404551437592,27700815674032,2504332323669064,
%U A215900 22702140562948192,2470653950084307472,24626774613248937584
%N A215900 Number of diagonal and antidiagonal neighbor colorings of the even squares of an nX3 array with new integer colors introduced in row major order.
%C A215900 Column 3 of A215904
%H A215900 R. H. Hardin, <a href="/A215900/b215900.txt">Table of n, a(n) for n = 1..96</a>
%e A215900 Some solutions for n=3
%e A215900 ..0..x..1....0..x..1....0..x..1....0..x..1....0..x..0....0..x..1....0..x..0
%e A215900 ..x..2..x....x..2..x....x..2..x....x..2..x....x..1..x....x..2..x....x..1..x
%e A215900 ..1..x..3....3..x..0....3..x..4....1..x..1....0..x..0....1..x..0....2..x..3
%K A215900 nonn
%O A215900 1,1
%A A215900 _R. H. Hardin_ Aug 26 2012