A208857 - OEIS

%I #6 Dec 18 2015 18:18:04

%S 1,11,5796,44452082,4071491223248,4445765748006060562,

%T 57867813487534623493632032,8978812485595759770697498996138448

%N Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors

%C Diagonal of A208864

%e Some solutions for n=4

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

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 02 2012