login
A230647
Number of nX3 0..2 white square subarrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value 2-x(i,j)
1
0, 3, 3, 21, 27, 177, 231, 1509, 1971, 12873, 16815, 109821, 143451, 936897, 1223799, 7992789, 10440387, 68187513, 89068287, 581716461, 759853035, 4962698097, 6482404167, 42337417029, 55302225363, 361185960873, 471790411599
OFFSET
1,2
COMMENTS
Column 3 of A230652
LINKS
FORMULA
Empirical: a(n) = 9*a(n-2) -4*a(n-4).
Empirical: G.f. -3*x^2*(2*x+1)*(x-1) / ( 1-9*x^2+4*x^4 ). - R. J. Mathar, Oct 27 2013
EXAMPLE
Some solutions for n=5
..0..x..0....0..x..0....1..x..1....0..x..0....2..x..2....0..x..0....2..x..2
..x..2..x....x..2..x....x..1..x....x..2..x....x..0..x....x..2..x....x..0..x
..2..x..0....0..x..0....1..x..1....0..x..2....1..x..1....2..x..2....1..x..2
..x..0..x....x..2..x....x..2..x....x..0..x....x..1..x....x..0..x....x..1..x
..2..x..2....0..x..0....0..x..0....2..x..2....1..x..1....2..x..2....1..x..1
CROSSREFS
Sequence in context: A205452 A159910 A172485 * A130723 A369078 A209528
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 27 2013
STATUS
approved