A240514 Number of nX3 0..1 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..1 introduced in row major order.

3, 6, 10, 28, 73, 196, 515, 1376, 3686, 9914, 26681, 71876, 193749, 522510, 1409414, 3802164, 10257707, 27675148, 74669353, 201466240, 543583450, 1466670482, 3957312647, 10677488468, 28809678971, 77733469590, 209738364682

Offset: 1

Author

R. H. Hardin, Apr 06 2014

Keywords

• nonn

Comments

Column 3 of A240519

Examples

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

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -3*a(n-2) -2*a(n-3) +2*a(n-4) +2*a(n-5) -7*a(n-6) -8*a(n-7) +15*a(n-8) +4*a(n-9) -8*a(n-10) -4*a(n-11) +15*a(n-12) +8*a(n-13) -7*a(n-14) -2*a(n-15) +2*a(n-16) +2*a(n-17) -3*a(n-18) -4*a(n-19) -a(n-20)