cp's OEIS Frontend

A231646 Number of nX3 0..2 arrays with no element less than a strict majority of its horizontal and vertical neighbors.

%I A231646 #6 Jul 23 2025 06:35:54
%S A231646 9,104,920,7682,61574,490760,3929027,31501117,252454167,2022844426,
%T A231646 16209670759,129896538285,1040912909763,8341204621591,66841228911422,
%U A231646 535624801555647,4292168448581044,34394795269925139,275618732897288063
%N A231646 Number of nX3 0..2 arrays with no element less than a strict majority of its horizontal and vertical neighbors.
%C A231646 Column 3 of A231651
%H A231646 R. H. Hardin, <a href="/A231646/b231646.txt">Table of n, a(n) for n = 1..210</a>
%F A231646 Empirical: a(n) = 18*a(n-1) -133*a(n-2) +640*a(n-3) -2309*a(n-4) +5762*a(n-5) -9918*a(n-6) +8864*a(n-7) +2970*a(n-8) -18151*a(n-9) +23183*a(n-10) +21799*a(n-11) -75109*a(n-12) +56329*a(n-13) -9892*a(n-14) -115814*a(n-15) +105665*a(n-16) +64162*a(n-17) -38348*a(n-18) +8767*a(n-19) +54790*a(n-20) -95246*a(n-21) -139155*a(n-22) +81259*a(n-23) +104482*a(n-24) +18968*a(n-25) -2909*a(n-26) -41630*a(n-27) -37578*a(n-28) +6670*a(n-29) +17693*a(n-30) +5629*a(n-31) -713*a(n-32) -928*a(n-33) -300*a(n-34) -52*a(n-35) -4*a(n-36) for n>37
%e A231646 Some solutions for n=3
%e A231646 ..1..0..0....2..0..0....2..1..1....1..1..2....2..1..0....0..0..0....0..2..1
%e A231646 ..1..0..0....0..0..1....2..1..2....1..1..1....2..0..0....0..1..2....0..0..1
%e A231646 ..1..1..0....0..2..1....2..1..1....2..2..1....0..0..1....0..1..2....2..0..0
%K A231646 nonn
%O A231646 1,1
%A A231646 _R. H. Hardin_, Nov 12 2013