A208375 Number of n X 4 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 1 0 1 vertically.

10, 100, 240, 420, 640, 900, 1200, 1540, 1920, 2340, 2800, 3300, 3840, 4420, 5040, 5700, 6400, 7140, 7920, 8740, 9600, 10500, 11440, 12420, 13440, 14500, 15600, 16740, 17920, 19140, 20400, 21700, 23040, 24420, 25840, 27300, 28800, 30340, 31920, 33540

Offset

1,1

Comments

Column 4 of A208379.

Links

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

Formula

Empirical: a(n) = 20*n^2 + 40*n - 60 for n>1.

Conjectures from Colin Barker, Jul 02 2018: (Start)

G.f.: 10*x*(1 + 7*x - 3*x^2 - x^3) / (1 - x)^3.

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

(End)

Example

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

Crossrefs

Cf. A208379.

Sequence in context: A044342 A119052 A029774 * A208065 A207930 A207847

Adjacent sequences: A208372 A208373 A208374 * A208376 A208377 A208378

Keyword

nonn

Author

R. H. Hardin, Feb 25 2012

Status

approved