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A255221 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 0 and no row sum 2 and no column sum 2. 1

%I #7 Dec 19 2018 09:04:04

%S 23,22,31,43,61,88,127,184,268,391,571,835,1222,1789,2620,3838,5623,

%T 8239,12073,17692,25927,37996,55684,81607,119599,175279,256882,376477,

%U 551752,808630,1185103,1736851,2545477,3730576,5467423,8012896,11743468

%N Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 0 and no row sum 2 and no column sum 2.

%H R. H. Hardin, <a href="/A255221/b255221.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) for n>5.

%F Empirical g.f.: x*(23 - 24*x + 10*x^2 - 20*x^3 + 7*x^4) / ((1 - x)*(1 - x - x^3)). - _Colin Barker_, Dec 19 2018

%e Some solutions for n=4:

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

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

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

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

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

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

%Y Column 1 of A255228.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 17 2015

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Last modified March 28 11:59 EDT 2024. Contains 371254 sequences. (Running on oeis4.)