A208639 Number of 4 X n 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, 34, 95, 225, 494, 1042, 2149, 4375, 8840, 17784, 35687, 71509, 143170, 286510, 573209, 1146627, 2293484, 4587220, 9174715, 18349729, 36699782, 73399914, 146800205, 293600815, 587202064, 1174404592, 2348809679, 4697619885

Offset: 1

Author

R. H. Hardin, Feb 29 2012

Keywords

• nonn

Comments

Row 4 of A208637.

Examples

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

Links

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

Crossrefs

Cf. A208637.

Formula

Empirical: a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4) for n>5.

Conjectures from Colin Barker, Jul 05 2018: (Start)

G.f.: x*(8 - 6*x - 3*x^2 + 2*x^4) / ((1 - x)^3*(1 - 2*x)).

a(n) = (-42 + 35*2^n - 13*n - n^2) / 2 for n>1.

(End)