login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A185791
Number of (n+1) X 3 binary arrays with no 2 X 2 subblock sum equal to any horizontal or vertical neighbor 2 X 2 subblock sum.
1
40, 96, 224, 576, 1408, 3456, 8320, 20864, 50816, 125312, 304768, 756096, 1844864, 4548992, 11110016, 27429248, 67069568, 165194112, 404309632, 995805568, 2438669952, 6000273792, 14703462016, 36167944576, 88660698752, 217982249344
OFFSET
1,1
COMMENTS
Column 2 of A185798.
LINKS
FORMULA
Empirical: a(n) = a(n-1) + 2*a(n-2) + 16*a(n-4) - 16*a(n-5).
Empirical g.f.: 8*x*(5 + 7*x + 6*x^2 + 20*x^3 - 32*x^4) / (1 - x - 2*x^2 - 16*x^4 + 16*x^5). - Colin Barker, Apr 16 2018
EXAMPLE
Some solutions for 5 X 3:
..0..1..0....1..1..1....1..0..0....0..0..1....0..0..0....0..0..1....0..1..1
..1..0..0....0..1..1....0..0..0....0..0..1....1..1..0....0..0..1....0..1..1
..0..0..0....0..0..1....0..0..1....0..1..1....1..0..1....1..1..1....0..0..0
..0..0..1....0..0..0....1..0..1....0..1..1....0..1..1....1..0..0....1..1..0
..0..1..1....1..0..0....0..1..1....0..0..0....0..0..0....0..0..0....1..0..1
CROSSREFS
Cf. A185798.
Sequence in context: A279689 A063310 A211493 * A092889 A235280 A235271
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 04 2011
STATUS
approved