OFFSET
0,2
COMMENTS
Diagonal of A188866.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..2000 (terms n = 1..32 from R. H. Hardin)
FORMULA
G.f.: (3*x^2-3*x+1-x*sqrt(1-3*x^2-2*x))/(1-3*x)^2. - Alois P. Heinz, Mar 30 2017
EXAMPLE
Some solutions for 3X3
..1..1..1....0..0..0....1..1..1....1..1..1....1..1..0....1..1..1....1..1..1
..1..1..1....0..0..0....1..1..1....1..0..0....0..0..0....1..1..1....1..1..1
..1..1..0....0..0..0....1..0..0....0..0..0....0..0..0....1..0..1....0..0..0
MAPLE
a:= proc(n) option remember; `if`(n<3, (2*n-1)*n+1,
((10*n^2-49*n+33)*a(n-1)-(6*n^2-9*n-33)*a(n-2)
-(9*(n-3))*(2*n-7)*a(n-3))/((n-1)*(2*n-9)))
end:
seq(a(n), n=0..35); # Alois P. Heinz, Mar 30 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 12 2011
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Mar 30 2017
STATUS
approved