login
A183324
Number of nX3 binary arrays with each 1 adjacent to exactly two other 1s
2
1, 3, 6, 10, 19, 37, 69, 129, 244, 460, 865, 1629, 3069, 5779, 10882, 20494, 38595, 72681, 136873, 257761, 485416, 914136, 1721505, 3241945, 6105241, 11497411, 21651966, 40775058, 76787731, 144606925, 272324269, 512842017, 965785884
OFFSET
1,2
COMMENTS
Column 3 of A183328
LINKS
FORMULA
Empirical: a(n)=2*a(n-1)-a(n-2)+2*a(n-3)-a(n-4).
Empirical: G.f. -x*(-1-x+x^3-x^2) / ( 1-2*x+x^2-2*x^3+x^4 ), see A033305 - R. J. Mathar, Sep 27 2013
EXAMPLE
All solutions for 4X3
..0..0..0....0..0..0....1..1..1....0..0..0....0..0..0....0..0..0....1..1..0
..0..0..0....0..0..0....1..0..1....1..1..1....0..1..1....1..1..0....1..1..0
..1..1..0....0..0..0....1..0..1....1..0..1....0..1..1....1..1..0....0..0..0
..1..1..0....0..0..0....1..1..1....1..1..1....0..0..0....0..0..0....0..0..0
...
..0..0..0....0..1..1....1..1..1
..0..0..0....0..1..1....1..0..1
..0..1..1....0..0..0....1..1..1
..0..1..1....0..0..0....0..0..0
CROSSREFS
Sequence in context: A091714 A017991 A065614 * A058356 A270048 A295719
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 03 2011
STATUS
approved