A208140 Number of n X 6 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.

16, 256, 1600, 6400, 19600, 50176, 112896, 230400, 435600, 774400, 1308736, 2119936, 3312400, 5017600, 7398400, 10653696, 15023376, 20793600, 28302400, 37945600, 50183056, 65545216, 84640000, 108160000, 136890000, 171714816

Offset: 1

Author

R. H. Hardin, Feb 23 2012

Keywords

• nonn

Comments

Column 6 of A208142.

Examples

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

Links

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

Crossrefs

Cf. A208142.

Formula

Empirical: a(n) = (4/9)*n^6 + (8/3)*n^5 + (52/9)*n^4 + (16/3)*n^3 + (16/9)*n^2.

Conjectures from Colin Barker, Jun 28 2018: (Start)

G.f.: 16*x*(1 + x)*(1 + 8*x + x^2) / (1 - x)^7.

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.

(End)