A207067 Number of n X 7 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically.

31, 961, 6634, 27063, 82739, 210118, 468348, 947298, 1776951, 3138223, 5275270, 8509345, 13254267, 20033564, 29499352, 42453012, 59867727, 82912941, 112980802, 151714651, 201039619, 263195394, 340771220, 436743190, 554513895, 697954491

Offset

1,1

Comments

Column 7 of A207068.

Links

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

Formula

Empirical: a(n) = (31/2520)*n^7 + (62/45)*n^6 + (4867/360)*n^5 + (2015/72)*n^4 + (1271/180)*n^3 - (4991/360)*n^2 - (713/140)*n.

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

G.f.: 31*x*(1 + 23*x - 6*x^2 - 27*x^3 + 11*x^4) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

Example

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

Crossrefs

Cf. A207068.

Sequence in context: A223393 A207390 A207518 * A207122 A207247 A208168

Adjacent sequences: A207064 A207065 A207066 * A207068 A207069 A207070

Keyword

nonn

Author

R. H. Hardin, Feb 14 2012

Status

approved