A207270 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 1 1 and 1 0 1 vertically

6, 36, 82, 217, 499, 1014, 2141, 4188, 8150, 15670, 29517, 55523, 103348, 191593, 353916, 651316, 1196664, 2193747, 4017137, 7347906, 13429145, 24530862, 44784850, 81739060, 149141623, 272067741, 496250336, 905026713, 1650411906

Offset

1,1

Comments

Row 3 of A207269

Links

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

Formula

Empirical: a(n) = a(n-1) +4*a(n-2) +2*a(n-3) -12*a(n-4) -9*a(n-5) +6*a(n-6) +20*a(n-7) +6*a(n-8) -2*a(n-9) -16*a(n-10) -12*a(n-11) -4*a(n-12) +14*a(n-13) +9*a(n-14) +a(n-15) -6*a(n-16) -2*a(n-17) +a(n-19)

Example

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

Crossrefs

Sequence in context: A208689 A207483 A207264 * A207763 A207347 A207769

Adjacent sequences: A207267 A207268 A207269 * A207271 A207272 A207273

Keyword

nonn

Author

R. H. Hardin Feb 16 2012

Status

approved