A209225 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 0 and 1 1 1 vertically.

9, 81, 126, 196, 504, 1296, 3312, 8464, 21712, 55696, 142544, 364816, 934992, 2396304, 6136272, 15713296, 40258384, 103144336, 264177872, 676624144, 1733335632, 4440356496, 11373699024, 29133027856, 74627823952, 191168323984

Offset

1,1

Comments

Row 4 of A209224.

Links

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

Formula

Empirical: a(n) = a(n-1) + 4*a(n-3) + 16*a(n-4) for n>7.

Empirical g.f.: x*(9 + 72*x + 45*x^2 + 34*x^3 - 160*x^4 - 1008*x^5 - 784*x^6) / ((1 + 4*x^2)*(1 - x - 4*x^2)). - Colin Barker, Jul 08 2018

Example

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

Crossrefs

Cf. A209224.

Sequence in context: A161147 A209220 A207689 * A208502 A175370 A207695

Adjacent sequences: A209222 A209223 A209224 * A209226 A209227 A209228

Keyword

nonn

Author

R. H. Hardin, Mar 06 2012

Status

approved