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 A268624 Number of n X 4 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once. 1

%I

%S 60,666,6300,55452,467190,3819654,30553014,240364746,1866503592,

%T 14342680944,109265781870,826421076378,6212333663082,46453421706210,

%U 345772280726172,2563402622459652,18936504080614278,139446644995253358

%N Number of n X 4 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once.

%H R. H. Hardin, <a href="/A268624/b268624.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 18*a(n-1) - 111*a(n-2) + 282*a(n-3) - 333*a(n-4) + 180*a(n-5) - 36*a(n-6) for n>7.

%F Empirical g.f.: 6*x*(10 - 69*x + 162*x^2 - 157*x^3 + 87*x^4 - 36*x^5 + 8*x^6) / (1 - 9*x + 15*x^2 - 6*x^3)^2.- _Colin Barker_, Jan 14 2019

%e Some solutions for n=4:

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

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

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

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

%Y Column 4 of A268628.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 09 2016

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Last modified January 19 05:41 EST 2022. Contains 350464 sequences. (Running on oeis4.)