A207919 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.

10, 100, 358, 1309, 4181, 13759, 46800, 156135, 518564, 1734968, 5800213, 19351425, 64616191, 215842982, 720736677, 2406625466, 8036934640, 26838643787, 89622848751, 299284174725, 999425753876, 3337450100119, 11144976639396

Offset: 1

Author

R. H. Hardin Feb 21 2012

Keywords

• nonn

Comments

Row 4 of A207918

Examples

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

Links

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

Formula

Empirical: a(n) = a(n-1) +2*a(n-2) +18*a(n-3) +15*a(n-4) -6*a(n-5) -70*a(n-6) -96*a(n-7) -14*a(n-8) +154*a(n-9) +147*a(n-10) -113*a(n-12) -71*a(n-13) -9*a(n-14) +33*a(n-15) +12*a(n-16) -a(n-17) -7*a(n-18) +3*a(n-19) +a(n-20) +2*a(n-21) for n>22