A207243 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 0 1 0 vertically

6, 36, 102, 283, 699, 1526, 3355, 6888, 13954, 27816, 54211, 105147, 201340, 382799, 723838, 1359688, 2544322, 4740623, 8801291, 16292518, 30071783, 55371672, 101727342, 186506700, 341316455, 623552411, 1137394900, 2071676507

Offset

1,1

Comments

Row 3 of A207242

Links

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

Formula

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

Example

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

Crossrefs

Sequence in context: A207747 A208023 A207961 * A207237 A207070 A207118

Adjacent sequences: A207240 A207241 A207242 * A207244 A207245 A207246

Keyword

nonn

Author

R. H. Hardin Feb 16 2012

Status

approved