A208119 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 0 1 1 vertically.

9, 81, 225, 625, 3025, 14641, 53361, 194481, 815409, 3418801, 13359025, 52200625, 211266225, 855036081, 3400172721, 13521270961, 54243807409, 217611987121, 869173967025, 3471607400625, 13896604674225, 55627148806321

Offset

1,1

Comments

Row 4 of A208118.

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 10*a(n-2) + 30*a(n-3) - 120*a(n-5) + 160*a(n-6) - 320*a(n-7) + 256*a(n-8).

Empirical g.f.: x*(9 + 36*x - 90*x^2 + 40*x^3 - 280*x^4 + 96*x^5 - 64*x^6 + 256*x^7) / ((1 - x)*(1 - 2*x)*(1 + 2*x)*(1 - 4*x)*(1 + 2*x^2)*(1 + 8*x^2)). - Colin Barker, Jun 28 2018

Example

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

Crossrefs

Cf. A208118.

Sequence in context: A016946 A144938 A208114 * A207369 A208014 A208556

Adjacent sequences: A208116 A208117 A208118 * A208120 A208121 A208122

Keyword

nonn

Author

R. H. Hardin, Feb 23 2012

Status

approved