A207364 Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 0 1 1 vertically.

9, 81, 252, 784, 1736, 3844, 7130, 13225, 21965, 36481, 56154, 86436, 125832, 183184, 255516, 356409, 480585, 648025, 850080, 1115136, 1429824, 1833316, 2305862, 2900209, 3588221, 4439449, 5414990, 6604900, 7956720, 9585216, 11421144

Offset

1,1

Comments

Column 4 of A207368.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 4*a(n-2) - 10*a(n-3) - 5*a(n-4) + 20*a(n-5) - 20*a(n-7) + 5*a(n-8) + 10*a(n-9) - 4*a(n-10) - 2*a(n-11) + a(n-12).

Empirical g.f.: x*(9 + 63*x + 54*x^2 + 46*x^3 + 15*x^4 - 19*x^5 - 22*x^6 + 9*x^7 + 10*x^8 - 4*x^9 - 2*x^10 + x^11) / ((1 - x)^7*(1 + x)^5). - Colin Barker, Jun 22 2018

Example

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

Crossrefs

Cf. A207368.

Sequence in context: A207560 A207415 A207020 * A207786 A223189 A207781

Adjacent sequences: A207361 A207362 A207363 * A207365 A207366 A207367

Keyword

nonn

Author

R. H. Hardin, Feb 17 2012

Status

approved