A208016 Number of 6 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 0 1 1 vertically.

16, 256, 784, 4489, 15376, 43264, 167281, 609961, 1974025, 6927424, 24750625, 84456100, 291931396, 1024704121, 3549895561, 12285283921, 42796024384, 148698928225, 515713569424, 1792246207504, 6227984421649, 21622397700121

Offset

1,1

Comments

Row 6 of A208013.

Links

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

Formula

Empirical: a(n) = a(n-1) + 3*a(n-2) + 21*a(n-3) + 9*a(n-4) - 27*a(n-5) - 81*a(n-6) for n>8.

Empirical g.f.: x*(16 + 240*x + 480*x^2 + 2601*x^3 + 3015*x^4 - 3915*x^5 - 15228*x^6 - 8505*x^7) / ((1 + 3*x^2 - 9*x^3)*(1 - x - 6*x^2 - 9*x^3)). - Colin Barker, Jun 26 2018

Example

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

Crossrefs

Cf. A208013.

Sequence in context: A017570 A208121 A207371 * A208558 A207349 A207771

Adjacent sequences: A208013 A208014 A208015 * A208017 A208018 A208019

Keyword

nonn

Author

R. H. Hardin, Feb 22 2012

Status

approved