A208710 Number of 3 X n 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

4, 32, 196, 1268, 8128, 52184, 334948, 2149988, 13800400, 88582472, 568596052, 3649722932, 23426960800, 150373741496, 965223885508, 6195610615940, 39768587869168, 255267911291816, 1638522010126516, 10517398618896212

Offset

1,1

Comments

Row 3 of A208709.

Links

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

Formula

Empirical: a(n) = 5*a(n-1) + 9*a(n-2) + a(n-3) - 2*a(n-4).

Empirical g.f.: 4*x*(1 + 3*x - x^3) / ((1 + x)*(1 - 6*x - 3*x^2 + 2*x^3)). - Colin Barker, Jul 06 2018

Example

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

Crossrefs

Cf. A208709.

Sequence in context: A270178 A018215 A099133 * A043018 A270015 A271161

Adjacent sequences: A208707 A208708 A208709 * A208711 A208712 A208713

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Status

approved