Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #4 Nov 08 2016 12:32:06
%S 0,30,410,6372,98410,1516632,23376048,360279838,5552721246,
%T 85579707940,1318971923980,20328262601458,313303293592114,
%U 4828693685579504,74420802953575212,1146988455048830360,17677617866311586368
%N Number of 3Xn 0..2 arrays with every element plus 1 mod 3 equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero.
%C Row 3 of A278014.
%H R. H. Hardin, <a href="/A278016/b278016.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 18*a(n-1) -32*a(n-2) -102*a(n-3) -406*a(n-4) +1452*a(n-5) +2596*a(n-6) +2458*a(n-7) -22648*a(n-8) -18454*a(n-9) +18879*a(n-10) +122984*a(n-11) -5236*a(n-12) -144156*a(n-13) -72858*a(n-14) +40286*a(n-15) +58052*a(n-16) +2232*a(n-17) -1856*a(n-18) -4224*a(n-19)
%e Some solutions for n=4
%e ..0..1..0..2. .0..2..0..2. .0..1..2..0. .0..1..2..1. .0..2..1..1
%e ..0..2..1..0. .1..0..1..2. .1..2..0..1. .0..2..0..1. .1..2..1..2
%e ..2..0..2..2. .0..2..1..0. .2..0..1..0. .1..1..2..2. .0..1..0..0
%Y Cf. A278014.
%K nonn
%O 1,2
%A _R. H. Hardin_, Nov 08 2016