A303630 - OEIS

%I #6 Sep 16 2020 19:06:41

%S 0,1,0,4,20,394,7538,501126,43679228,8515657512,2784504147786

%N Number of n X n 0..1 arrays with every element unequal to 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.

%C Diagonal of A303636.

%e Some solutions for n=5

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

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

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

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

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

%Y Cf. A303636.

%K nonn

%O 1,4

%A _R. H. Hardin_, Apr 27 2018