A199145 - OEIS

%I #9 Oct 03 2025 08:06:55

%S 2,65,2453,125468,6235011,316561994,15958823113,806680624447,

%T 40736752748774,2057896226081573,103945296750116087,

%U 5250572116269762125,265216743260845702081,13396704712673136390007,676696655003807234547723

%N Number of nX4 0..3 arrays with values 0..3 introduced in row major order and each element equal to one or two horizontal and vertical neighbors.

%C Column 4 of A199149

%H R. H. Hardin, <a href="/A199145/b199145.txt">Table of n, a(n) for n = 1..200</a>

%e Some solutions for n=3

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

%e ..2..2..2..3....1..2..3..1....0..2..3..0....0..1..0..2....0..0..2..2

%e ..0..0..3..3....1..2..3..3....0..2..3..0....1..1..2..2....2..2..0..0

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 03 2011