A208633 Number of n X 4 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.

8, 23, 71, 225, 722, 2331, 7548, 24476, 79423, 257807, 836973, 2717446, 8823199, 28648292, 93019712, 302032007, 980690055, 3184277945, 10339281402, 33571429395, 109005736508, 353939387572, 1149233948207, 3731539152111

Offset: 1

Author

R. H. Hardin, Feb 29 2012

Keywords

• nonn

Comments

Column 4 of A208637.

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A208637.

Formula

Empirical: a(n) = 5*a(n-1) - 6*a(n-2) + a(n-3).

Empirical g.f.: x*(8 - 17*x + 4*x^2) / (1 - 5*x + 6*x^2 - x^3). - Colin Barker, Jul 05 2018