A207064 Number of n X 4 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically.

9, 81, 288, 720, 1485, 2709, 4536, 7128, 10665, 15345, 21384, 29016, 38493, 50085, 64080, 80784, 100521, 123633, 150480, 181440, 216909, 257301, 303048, 354600, 412425, 477009, 548856, 628488, 716445, 813285, 919584, 1035936, 1162953

Offset

1,1

Comments

Column 4 of A207068.

Links

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

Formula

Empirical: a(n) = (3/4)*n^4 + (15/2)*n^3 + (15/4)*n^2 - 3*n.

Conjectures from Colin Barker, Jun 18 2018: (Start)

G.f.: 9*x*(1 + 4*x - 3*x^2) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

Example

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

Crossrefs

Cf. A207068.

Sequence in context: A207496 A208165 A207244 * A207119 A207399 A207904

Adjacent sequences: A207061 A207062 A207063 * A207065 A207066 A207067

Keyword

nonn

Author

R. H. Hardin, Feb 14 2012

Status

approved