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Number of nX6 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two exactly once.
1

%I #4 Feb 09 2016 12:22:18

%S 240,7128,163878,3440052,68710116,1328460312,25093766490,465757993812,

%T 8527096170390,154406753980596,2770879234068744,49351916066147196,

%U 873425626212657504,15373652306609086368,269322517606253198046

%N Number of nX6 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two exactly once.

%C Column 6 of A268639.

%H R. H. Hardin, <a href="/A268637/b268637.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 60*a(n-1) -1482*a(n-2) +20016*a(n-3) -167163*a(n-4) +924894*a(n-5) -3537110*a(n-6) +9593166*a(n-7) -18693789*a(n-8) +26218062*a(n-9) -26188161*a(n-10) +18139608*a(n-11) -8262712*a(n-12) +2220864*a(n-13) -266256*a(n-14) for n>15

%e Some solutions for n=3

%e ..0..0..1..2..2..2. .0..1..2..1..0..0. .1..1..0..0..0..1. .0..1..2..1..0..0

%e ..0..1..2..2..2..2. .1..2..1..2..1..1. .0..0..0..0..0..0. .0..0..1..2..1..0

%e ..1..0..2..2..2..1. .2..1..2..1..0..0. .0..0..0..1..0..0. .1..1..2..1..0..1

%Y Cf. A268639.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 09 2016