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A297432 Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s. 1

%I

%S 1,2,7,12,18,33,73,139,244,449,880,1680,3105,5781,10981,20806,39007,

%T 73112,137842,260073,489213,919503,1730944,3260449,6136804,11545760,

%U 21729985,40908585,77001561,144914586,272743111,513379012,966299842

%N Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s.

%H R. H. Hardin, <a href="/A297432/b297432.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) + a(n-3) + 4*a(n-4).

%F Empirical g.f.: x*(1 + x + 5*x^2 + 4*x^3) / (1 - x - x^3 - 4*x^4). - _Colin Barker_, Feb 28 2019

%e Some solutions for n=5:

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

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

%Y Row 2 of A297431.

%K nonn

%O 1,2

%A _R. H. Hardin_, Dec 30 2017

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Last modified April 11 14:29 EDT 2021. Contains 342886 sequences. (Running on oeis4.)