A207112 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically

6, 36, 98, 271, 677, 1504, 3399, 7220, 15184, 31664, 64749, 132543, 268994, 544151, 1099824, 2215226, 4461522, 8974915, 18040615, 36261642, 72844037, 146324852, 293885650, 590165228, 1185140667, 2379732659, 4778367860, 9594547523

Offset

1,1

Comments

Row 3 of A207111

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +3*a(n-2) -2*a(n-3) -13*a(n-4) +3*a(n-5) +13*a(n-6) +9*a(n-7) -12*a(n-8) -2*a(n-9) -3*a(n-10) -a(n-11) -2*a(n-12) +8*a(n-13) +a(n-14) -2*a(n-15) -2*a(n-16) +a(n-17)

Example

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

Crossrefs

Sequence in context: A192278 A207106 A207306 * A207392 A207939 A207462

Adjacent sequences: A207109 A207110 A207111 * A207113 A207114 A207115

Keyword

nonn

Author

R. H. Hardin Feb 15 2012

Status

approved