A207591 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 1 1 vertically.

9, 81, 144, 432, 1098, 3150, 8244, 23202, 61560, 171468, 458640, 1269144, 3412944, 9402156, 25378560, 69694632, 188620632, 516830904, 1401394608, 3833746488, 10409369472, 28443841344, 77305743936, 211065666624, 574042728672

Offset: 1

Author

R. H. Hardin, Feb 19 2012

Keywords

• nonn

Comments

Row 4 of A207589.

Examples

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

Links

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

Crossrefs

Cf. A207589.

Formula

Empirical: a(n) = 8*a(n-2) + 2*a(n-3) - 10*a(n-4) + 2*a(n-6) for n>8.

Empirical g.f.: 9*x*(1 - x)*(1 + 10*x + 18*x^2 - 8*x^3 - 22*x^4 + 2*x^5 + 4*x^6) / (1 - 8*x^2 - 2*x^3 + 10*x^4 - 2*x^6). - Colin Barker, Jun 24 2018