A207369 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 0 1 1 vertically.

9, 81, 225, 784, 2304, 5625, 14641, 33856, 77284, 173056, 372100, 795664, 1664100, 3433609, 7017201, 14160169, 28355625, 56310016, 111007296, 217533001, 423742225, 821280964, 1584358416, 3043287556, 5823216100, 11102415424

Offset: 1

Author

R. H. Hardin Feb 17 2012

Keywords

• nonn

Comments

Row 4 of A207368

Examples

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

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -a(n-2) -8*a(n-3) -10*a(n-4) +30*a(n-5) +11*a(n-6) -15*a(n-7) -43*a(n-8) +21*a(n-9) -5*a(n-10) +26*a(n-11) +a(n-12) +27*a(n-13) -42*a(n-14) +3*a(n-15) -14*a(n-16) +15*a(n-17) -9*a(n-18) +17*a(n-19) -6*a(n-20) +2*a(n-21) -4*a(n-22) +2*a(n-23) -2*a(n-24) +a(n-25)