A218349 Hilltop maps: number of nX3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..1 nX3 array.

5, 41, 291, 2069, 14811, 105913, 757305, 5415209, 38722037, 276885777, 1979899795, 14157473937, 101234450215, 723887182917, 5176228570197, 37013146305509, 264666248964889, 1892522801570497, 13532675845407459, 96766768350125913

Offset: 1

Author

R. H. Hardin Oct 26 2012

Keywords

• nonn

Comments

Column 3 of A218354

Examples

			Some solutions for n=3
..1..1..1....1..1..0....1..1..0....1..1..1....0..0..1....1..1..1....1..1..0
..0..0..1....1..1..1....1..1..1....0..1..1....1..0..1....1..1..1....0..0..0
..0..1..1....0..0..0....0..1..0....1..1..0....1..0..0....0..1..0....1..1..1
		

Links

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

Formula

Empirical: a(n) = 6*a(n-1) +5*a(n-2) +22*a(n-3) +7*a(n-4) +8*a(n-5) -18*a(n-6) -20*a(n-7) -a(n-8) +4*a(n-9) +3*a(n-10) +a(n-12)