A302624 - OEIS

%I #4 Apr 10 2018 19:13:50

%S 4,25,25,45,79,146,286,563,1114,2222,4435,8858,17710,35411,70810,

%T 141614,283219,566426,1132846,2265683,4531354,9062702,18125395,

%U 36250778,72501550,145003091,290006170,580012334,1160024659,2320049306,4640098606

%N Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

%C Row 3 of A302623.

%H R. H. Hardin, <a href="/A302624/b302624.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) +a(n-3) -2*a(n-4) for n>8

%e Some solutions for n=5

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

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

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

%Y Cf. A302623.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 10 2018