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

%I #4 Feb 18 2016 08:58:00

%S 240,2208,44760,785124,13031664,208867428,3266423688,50155587360,

%T 759280601376,11364951702132,168545724611088,2480433137331636,

%U 36267257458624740,527333427504496308,7630684978884541020

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

%C Column 6 of A269035.

%H R. H. Hardin, <a href="/A269033/b269033.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 36*a(n-1) -436*a(n-2) +1854*a(n-3) +340*a(n-4) -19128*a(n-5) +23849*a(n-6) +56184*a(n-7) -108224*a(n-8) -40816*a(n-9) +160400*a(n-10) -34136*a(n-11) -83203*a(n-12) +42628*a(n-13) +6468*a(n-14) -6334*a(n-15) +204*a(n-16) +240*a(n-17) -25*a(n-18) for n>19

%e Some solutions for n=3

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

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

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

%Y Cf. A269035.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 18 2016