A198899 Number of n X n 0..4 arrays with values 0..4 introduced in row major order and no element equal to any horizontal or vertical neighbor.

1, 4, 1211, 6907736, 423503301834, 274342896958292170, 1877611081501313948217870, 135766460737448561825230968357842

Offset: 1

Author

R. H. Hardin Oct 31 2011

Keywords

• nonn

Comments

Diagonal of A198906

Examples

			Some solutions with values 0 to 4 for n=4
..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1
..1..2..1..0....1..2..1..2....1..2..1..2....1..0..2..0....1..0..1..0
..0..1..3..4....2..3..0..1....3..0..2..0....3..4..0..3....2..1..0..3
..3..2..0..3....4..1..2..4....4..3..1..3....2..1..2..4....1..4..1..2
		

Links

• Jean-François Alcover, Table of n, a(n) for n = 1..14

Programs

Mathematica

A198906 = Cases[Import["https://oeis.org/A198906/b198906.txt", "Table"], {, }][[All, 2]];
a[n_] := A198906[[2 n^2 - 2 n + 1]];
Table[a[n], {n, 1, 14}] (* Jean-François Alcover, Sep 23 2019 *)