A198711 Number of n X 4 0..3 arrays with values 0..3 introduced in row major order and no element equal to any horizontal or vertical neighbor.

5, 172, 6548, 250031, 9548295, 364637102, 13925032958, 531779578441, 20307996787865, 775536991678112, 29616787512285048, 1131028064429979731, 43192546862380323515, 1649469330720040937602, 62991170251091380482818

Offset: 1

Author

R. H. Hardin, Oct 29 2011

Keywords

• nonn

Comments

Column 4 of A198715.

Examples

			Some solutions with all values from 0 to 3 for n=5:
..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1
..1..0..2..0....1..0..1..2....1..0..1..2....1..0..1..0....1..0..1..0
..0..2..0..3....2..1..3..1....3..1..0..1....2..1..0..3....2..1..3..1
..2..1..2..0....1..2..0..3....1..0..3..0....3..2..1..0....3..0..1..3
..1..2..1..2....2..3..1..2....2..1..0..1....2..1..3..2....2..3..0..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A198715.

Formula

Empirical: a(n) = 46*a(n-1) - 312*a(n-2) + 530*a(n-3) - 263*a(n-4).

Empirical g.f.: x*(5 - 58*x + 196*x^2 - 163*x^3) / ((1 - x)*(1 - 45*x + 267*x^2 - 263*x^3)). - Colin Barker, Mar 02 2018