%I #8 Apr 14 2020 21:35:22
%S 1,2,18,1082,560778,2666449962,116124404018058,45944873892068760842,
%T 164311405786753523443114218,5298327789094557001583255058644522,
%U 1538780360110790603716817054271433490324298
%N Number of n X n 0..2 arrays with new values introduced in each row and column in sequential order starting with zero.
%C Diagonal of A268056.
%H R. H. Hardin, <a href="/A268051/b268051.txt">Table of n, a(n) for n = 1..19</a>
%e Some solutions for n=4
%e ..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
%e ..0..1..0..1....0..0..0..0....0..1..1..0....0..0..1..1....0..1..1..0
%e ..0..0..1..0....0..1..1..0....0..1..1..0....0..0..1..1....0..1..2..0
%e ..0..1..0..2....0..0..0..0....0..1..0..1....0..0..1..2....0..1..1..0
%Y Cf. A268056.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 25 2016