A198521 Number of n X n 0..4 arrays with values 0..4 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors.

1, 15, 16714, 1084539825, 1814002928583853, 72341858272434900016248

Offset: 1

Author

R. H. Hardin, Oct 26 2011

Keywords

• nonn
• more

Examples

			Some solutions for n=4:
..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
..0..1..1..2....0..1..1..1....0..1..1..0....0..1..1..1....0..1..1..2
..2..1..3..0....2..1..3..4....2..1..3..0....2..1..0..2....3..0..0..3
..1..2..1..0....1..3..4..0....3..0..0..0....2..0..0..2....3..4..0..1
		

Crossrefs

Diagonal of A198528.