A202797 Number of n X 3 binary arrays with every one adjacent to another one horizontally or vertically.

4, 36, 250, 1718, 11988, 83518, 581518, 4049700, 28202318, 196400270, 1367728548, 9524845126, 66330898142, 461927514284, 3216857242006, 22402152254494, 156008298702684, 1086439775514766, 7565952552767646, 52689195775528564

Offset: 1

Author

R. H. Hardin, Dec 24 2011

Keywords

• nonn

Comments

Column 3 of A202802.

Examples

			Some solutions for n=5:
..0..0..0....0..1..0....0..0..1....0..1..1....0..1..1....0..0..1....0..0..0
..1..0..0....1..1..1....0..0..1....0..1..0....0..0..1....0..0..1....1..0..0
..1..0..0....0..0..1....1..0..1....1..0..0....1..1..0....0..1..0....1..1..1
..0..1..1....0..1..0....1..1..1....1..1..1....0..0..0....0..1..1....1..1..1
..0..1..0....0..1..1....0..1..0....0..0..1....0..1..1....0..0..1....0..1..0
		

Links

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

Crossrefs

Cf. A202802.

Formula

Empirical: a(n) = 7*a(n-1) -3*a(n-2) +19*a(n-3) -3*a(n-4) +25*a(n-5) +24*a(n-6) -22*a(n-7) -16*a(n-8).

Empirical g.f.: 2*x*(2 + 4*x + 5*x^2 + 20*x^4 + 7*x^5 - 16*x^6 - 8*x^7) / (1 - 7*x + 3*x^2 - 19*x^3 + 3*x^4 - 25*x^5 - 24*x^6 + 22*x^7 + 16*x^8). - Colin Barker, Jun 01 2018