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A283517 Number of nX3 0..1 arrays with no 1 equal to more than three of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements. 1

%I

%S 0,1,20,270,2763,26662,241796,2115564,18020972,150431216,1235860816,

%T 10022560088,80412418752,639331124272,5043680344120,39521427506168,

%U 307850445104320,2385411084242780,18397022091700304,141285768645661084

%N Number of nX3 0..1 arrays with no 1 equal to more than three of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements.

%C Column 3 of A283522.

%H R. H. Hardin, <a href="/A283517/b283517.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 15*a(n-1) -36*a(n-2) -235*a(n-3) +171*a(n-4) +2481*a(n-5) +5734*a(n-6) +6894*a(n-7) +5364*a(n-8) +3397*a(n-9) +1947*a(n-10) +846*a(n-11) +277*a(n-12) +126*a(n-13) +12*a(n-14) +8*a(n-15) for n>19

%e Some solutions for n=4

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

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

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

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

%Y Cf. A283522.

%K nonn

%O 1,3

%A _R. H. Hardin_, Mar 09 2017

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Last modified June 28 21:04 EDT 2022. Contains 354907 sequences. (Running on oeis4.)