A183339 Number of nX7 binary arrays with each 1 adjacent to exactly one 1 vertically and one 1 horizontally.

1, 13, 37, 97, 407, 1397, 4531, 16029, 55471, 188735, 651517, 2246015, 7712899, 26544813, 91374201, 314289321, 1081352347, 3720918175, 12801778315, 44045879629, 151549077973, 521423489151, 1794025850189, 6172623965117

Offset: 1

Author

R. H. Hardin Jan 04 2011

Keywords

• nonn

Comments

Equivalent to all 1s connected only in 2X2 blocks

Column 7 of A183342

Examples

			Some solutions for 5X7
..0..0..0..1..1..0..0....1..1..0..0..0..0..0....0..0..0..0..1..1..0
..0..0..0..1..1..0..0....1..1..0..0..1..1..0....1..1..0..0..1..1..0
..0..0..0..0..0..1..1....0..0..0..0..1..1..0....1..1..0..0..0..0..0
..1..1..0..0..0..1..1....0..0..0..0..0..0..0....0..0..1..1..0..0..0
..1..1..0..0..0..0..0....0..0..0..0..0..0..0....0..0..1..1..0..0..0
		

Links

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

Formula

Empirical: a(n)=a(n-1)+2*a(n-2)+18*a(n-3)+17*a(n-4)+7*a(n-5)-40*a(n-6)-78*a(n-7)-21*a(n-8)+88*a(n-9)+62*a(n-10)-49*a(n-11)-24*a(n-12)+9*a(n-13)-18*a(n-14)+2*a(n-15)+9*a(n-16)+4*a(n-17)+4*a(n-18)