OFFSET
1,1
COMMENTS
Column 4 of A230989
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-2) -61*a(n-4) +148*a(n-6) -289*a(n-8) +325*a(n-10) -227*a(n-12) +95*a(n-14) -28*a(n-16) +4*a(n-18)
EXAMPLE
Some solutions for n=6
..0..x..1..x..1....0..x..0..x..0....0..x..0..x..0....0..x..0..x..1
..x..1..x..0..x....x..1..x..1..x....x..1..x..1..x....x..1..x..0..x
..0..x..1..x..1....0..x..0..x..1....1..x..1..x..0....0..x..0..x..1
..x..0..x..0..x....x..0..x..0..x....x..0..x..0..x....x..1..x..1..x
..1..x..0..x..1....1..x..1..x..0....1..x..1..x..0....1..x..0..x..1
..x..1..x..1..x....x..1..x..1..x....x..0..x..1..x....x..0..x..0..x
..0..x..0..x..0....0..x..0..x..0....1..x..1..x..0....1..x..1..x..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 02 2013
STATUS
approved