A207443 - OEIS

%I #9 Oct 03 2025 13:55:06

%S 6,36,108,323,1058,3223,9515,28426,84486,249106,734637,2166526,

%T 6380211,18782449,55296998,162765970,479038288,1409873905,4149367138,

%U 12211531035,35938252497,105765419940,311263342522,916033572652,2695845174863

%N Number of 3Xn 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 0 vertically.

%C Row 3 of A207442

%H R. H. Hardin, <a href="/A207443/b207443.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) -5*a(n-2) +16*a(n-3) -35*a(n-4) +19*a(n-5) -48*a(n-6) +80*a(n-7) +12*a(n-8) +52*a(n-9) -92*a(n-10) -54*a(n-11) -52*a(n-12) +76*a(n-13) +43*a(n-14) +32*a(n-15) -27*a(n-16) -16*a(n-17) -11*a(n-18) +5*a(n-19) +2*a(n-21)

%e Some solutions for n=4

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 17 2012