A230690 - OEIS

%I #5 Oct 27 2013 18:14:10

%S 2,4,21,139,913,6276,43544,301609,2092432,14518601,100730876,

%T 698916053,4849388894,33647114207,233458408129,1619836235637,

%U 11239129382534,77981980905001,541072982103756,3754200244270001,26048278095561922

%N Number of (n+2)X(1+2) 0..2 arrays x(i,j) with each element horizontally, vertically, diagonally or antidiagonally next to at least two elements with value (x(i,j)+1) mod 3, and upper left element zero

%C Column 1 of A230694

%H R. H. Hardin, <a href="/A230690/b230690.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 7*a(n-1) -2*a(n-2) +26*a(n-3) -115*a(n-4) +96*a(n-5) -242*a(n-6) +559*a(n-7) -460*a(n-8) +731*a(n-9) -1062*a(n-10) +238*a(n-11) -1160*a(n-12) +1284*a(n-13) +261*a(n-14) +936*a(n-15) -830*a(n-16) +1008*a(n-17) -453*a(n-19) +128*a(n-20) -5*a(n-21) -a(n-22)

%e Some solutions for n=3

%e ..0..2..0....0..2..0....0..1..0....0..1..0....0..1..0....0..2..0....0..1..0

%e ..1..1..1....1..1..1....2..1..2....2..1..2....2..1..2....1..1..1....2..1..2

%e ..2..1..2....2..0..2....1..0..1....2..0..2....1..0..0....0..2..0....0..2..0

%e ..0..0..0....1..0..1....2..2..2....1..0..1....2..1..2....1..1..1....1..1..1

%e ..2..1..2....2..0..2....1..0..1....2..0..2....0..1..0....0..2..0....0..2..0

%K nonn

%O 1,1

%A _R. H. Hardin_, Oct 27 2013