A183304 Half the number of n X 3 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.
1, 4, 9, 19, 42, 93, 205, 452, 997, 2199, 4850, 10697, 23593, 52036, 114769, 253131, 558298, 1231365, 2715861, 5990020, 13211405, 29138671, 64267362, 141746129, 312630929, 689529220, 1520804569, 3354240067, 7398009354, 16316823277
Offset: 1
Keywords
Examples
Some solutions with a(1,1)=0 for 3X4 ..0..1..0..1....0..0..1..1....0..1..0..1....0..1..0..0....0..1..1..0 ..1..0..0..1....1..1..0..0....0..1..1..0....1..0..1..1....1..0..0..1 ..0..1..1..0....0..1..0..1....1..0..1..0....0..1..0..0....0..1..1..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..200
Crossrefs
Column 3 of A183312.
Formula
Empirical: a(n) = 2*a(n-1)+a(n-3).
Empirical G.f.: x*(1+x)^2/(1-2*x-x^3). - Colin Barker, Feb 23 2012
Comments