A207449 Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 1 vertically.

10, 100, 330, 760, 1450, 2460, 3850, 5680, 8010, 10900, 14410, 18600, 23530, 29260, 35850, 43360, 51850, 61380, 72010, 83800, 96810, 111100, 126730, 143760, 162250, 182260, 203850, 227080, 252010, 278700, 307210, 337600, 369930, 404260, 440650

Offset

1,1

Comments

Column 4 of A207453.

Links

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

Formula

Empirical: a(n) = 10*n^3 + 10*n^2 - 10*n.

Conjectures from Colin Barker, Jun 22 2018: (Start)

G.f.: 10*x*(1 + 6*x - x^2) / (1 - x)^4.

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.

(End)

Example

Some solutions for n=5:
..1..0..1..0....1..0..1..0....1..1..1..0....0..1..1..0....1..1..0..0
..1..0..1..1....1..1..1..1....0..1..1..1....1..1..0..1....1..0..1..0
..1..0..1..1....0..1..0..1....0..1..0..0....1..1..0..0....1..0..1..0
..1..0..1..0....0..1..0..0....0..1..0..0....0..1..0..0....1..0..1..0
..1..0..1..0....0..1..0..0....0..1..0..0....0..1..0..0....1..0..1..0

Crossrefs

Cf. A207453.

Sequence in context: A305668 A262761 A134556 * A208551 A207308 A207114

Adjacent sequences: A207446 A207447 A207448 * A207450 A207451 A207452

Keyword

nonn

Author

R. H. Hardin, Feb 17 2012

Status

approved