A266013 - OEIS

%I #4 Dec 20 2015 06:59:40

%S 1,2,6,4,11,18,27,43,62,112,191,310,548,883,1467,2535,4210,6993,11848,

%T 19780,33042,55676,93207,155834,261837,438753,734590,1232614,2065881,

%U 3460646,5803604,9727967,16300819,27328897,45809212,76772793,128697166

%N Number of 3Xn integer arrays with each element equal to the number of horizontal and antidiagonal neighbors equal to itself.

%C Row 3 of A266012.

%H R. H. Hardin, <a href="/A266013/b266013.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-3) +2*a(n-4) +2*a(n-5) +a(n-6) -2*a(n-7) -2*a(n-8) -3*a(n-9) +2*a(n-10) +2*a(n-11) +5*a(n-12) -a(n-15) for n>19

%e All solutions for n=4

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

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

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

%Y Cf. A266012.

%K nonn

%O 1,2

%A _R. H. Hardin_, Dec 20 2015