%I #9 Sep 03 2022 23:18:20
%S 1,15,6451,40919141,2579588216958
%N Number of n X n 0..3 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..3 introduced in row major order.
%C Diagonal of A204685.
%e Some solutions for n=5
%e ..0..1..1..0..2....0..0..1..1..0....0..0..1..0..2....0..0..1..0..0
%e ..2..3..1..3..3....2..0..3..3..0....2..1..1..3..2....0..2..3..1..1
%e ..0..0..3..2..3....2..3..1..0..3....0..1..0..3..3....2..0..1..0..0
%e ..3..2..0..1..2....0..3..2..1..0....2..2..3..2..0....0..0..3..0..1
%e ..0..3..3..1..2....2..2..3..0..0....1..0..3..3..2....1..2..1..3..2
%Y Cf. A204685.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 18 2012