A207781 Number of nX4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 0 and 1 0 1 vertically.

9, 81, 257, 791, 2200, 6418, 19041, 55101, 160274, 468839, 1365913, 3979457, 11607265, 33840611, 98648082, 287610828, 838518475, 2444629303, 7127128826, 20778544998, 60578554943, 176612608043, 514899479923, 1501152602979

Offset: 1

Author

R. H. Hardin Feb 20 2012

Keywords

• nonn

Comments

Column 4 of A207785

Examples

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

Links

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

Formula

Empirical: a(n) = a(n-1) +16*a(n-3) +6*a(n-4) +6*a(n-5) -50*a(n-6) -40*a(n-7) -3*a(n-8) +56*a(n-9) +25*a(n-10) -10*a(n-11) -25*a(n-12) +38*a(n-13) -16*a(n-14) -19*a(n-15) +12*a(n-16) +25*a(n-17) +3*a(n-18) -10*a(n-19) -8*a(n-20) +13*a(n-21) -4*a(n-22) -11*a(n-23) +a(n-24) +5*a(n-25) -2*a(n-27) for n>31