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%I #7 May 09 2017 19:12:05
%S 1,1,2,4,12,34,136,500,2440,10900,61912,322768,2075312,12297768,
%T 87852160,580849872,4548247264,33093252880,281121815712,2227152575552,
%U 20358402201792,174131286983712,1701534399324544,15604440074084672
%N Number of horizontal, vertical and diagonal neighbor colorings of the even squares of an n X 2 array with new integer colors introduced in row major order.
%C Column 2 of A215959.
%H R. H. Hardin, <a href="/A215953/b215953.txt">Table of n, a(n) for n = 1..122</a>
%e Some solutions for n=5
%e ..0..x....0..x....0..x....0..x....0..x....0..x....0..x....0..x....0..x....0..x
%e ..x..1....x..1....x..1....x..1....x..1....x..1....x..1....x..1....x..1....x..1
%e ..1..x....1..x....2..x....2..x....2..x....1..x....2..x....1..x....2..x....1..x
%e ..x..0....x..2....x..3....x..3....x..0....x..0....x..0....x..2....x..3....x..2
%e ..0..x....0..x....1..x....0..x....1..x....2..x....0..x....3..x....4..x....2..x
%K nonn
%O 1,3
%A _R. H. Hardin_, Aug 28 2012