A207168 Number of n X 7 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 0 1 vertically

28, 784, 3808, 11452, 26908, 54208, 98224, 164668, 260092, 391888, 568288, 798364, 1092028, 1460032, 1913968, 2466268, 3130204, 3919888, 4850272, 5937148, 7197148, 8647744, 10307248, 12194812, 14330428, 16734928, 19429984, 22438108, 25782652

Offset

1,1

Comments

Column 7 of A207169.

Links

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

Formula

Empirical: a(n) = 35*n^4 + 42*n^3 + 7*n^2 - 84*n + 28.

Conjectures from Colin Barker, Jun 20 2018: (Start)

G.f.: 28*x*(1 + 23*x + 6*x^2 - x^3 + x^4) / (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:
..0..1..0..0..1..1..0....1..0..0..1..0..0..1....0..0..1..0..0..1..1
..1..1..0..0..1..1..1....0..1..1..1..1..1..1....0..1..1..1..1..1..0
..1..1..0..0..1..1..1....0..1..1..1..0..0..1....0..0..1..0..0..1..0
..0..1..0..0..1..0..0....0..0..1..1..0..0..1....0..0..1..0..0..1..0

Crossrefs

Cf. A207169.

Sequence in context: A207894 A207884 A207761 * A208012 A207789 A207304

Adjacent sequences: A207165 A207166 A207167 * A207169 A207170 A207171

Keyword

nonn

Author

R. H. Hardin, Feb 15 2012

Status

approved