A208121 Number of 6 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 0 1 1 vertically.

16, 256, 784, 2401, 17689, 130321, 577600, 2560000, 15054400, 88529281, 443060401, 2217373921, 12151975696, 66597028096, 346652467984, 1804403844961, 9669593502409, 51818243883121, 273150984198400, 1439868559360000

Offset

1,1

Comments

Row 6 of A208118.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 21*a(n-2) + 84*a(n-3) - 756*a(n-5) + 1701*a(n-6) - 5103*a(n-7) + 6561*a(n-8).

Empirical g.f.: x*(16 + 144*x - 672*x^2 + 945*x^3 - 4158*x^4 + 3159*x^5 + 1458*x^6 + 6561*x^7) / ((1 - 3*x)*(1 + 3*x)*(1 - 7*x + 9*x^2)*(1 + 21*x^2 + 81*x^4)). - Colin Barker, Jun 28 2018

Example

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

Crossrefs

Cf. A208118.

Sequence in context: A208837 A208685 A017570 * A207371 A208016 A208558

Adjacent sequences: A208118 A208119 A208120 * A208122 A208123 A208124

Keyword

nonn

Author

R. H. Hardin, Feb 23 2012

Status

approved