A240651 Number of nX3 0..1 arrays with no element equal to exactly one horizontal or vertical neighbor, with new values 0..1 introduced in row major order.

1, 2, 9, 17, 43, 136, 402, 1180, 3518, 10525, 31454, 94059, 281484, 842574, 2522415, 7552239, 22613578, 67714627, 202772197, 607215863, 1818375168, 5445371326, 16306993036, 48833947510, 146241553581, 437945846008, 1311506541151

Offset: 1

Author

R. H. Hardin, Apr 09 2014

Keywords

• nonn

Comments

Column 3 of A240656

Examples

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

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +a(n-2) +2*a(n-3) -11*a(n-4) -12*a(n-5) -9*a(n-6) +15*a(n-7) +23*a(n-8) +20*a(n-9) -6*a(n-10) -15*a(n-11) -12*a(n-12) -2*a(n-13) +3*a(n-14) +a(n-15)