A193501 - OEIS

%I #5 Dec 18 2015 18:17:42

%S 5,71,2558,250860,64996451,45170582886,83632270690739,

%T 415014359673696258,5503137668192072543375

%N Number of n X n symmetric 0..4 arrays with no element equal to the product mod 5 of any two of its horizontal and vertical neighbors

%e Some solutions for 4X4

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

%e ..0..2..2..2....3..1..0..2....1..0..1..3....0..1..2..3....1..4..0..3

%e ..2..2..3..3....1..0..1..0....0..1..0..4....3..2..3..1....3..0..2..2

%e ..2..2..3..0....0..2..0..3....1..3..4..0....1..3..1..4....2..3..2..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Jul 29 2011