OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 16*a(n-2) +3*a(n-4) -10*a(n-6) +24*a(n-8) -16*a(n-10).
Empirical g.f.: 2*x*(1 + 8*x + x^2 - 12*x^3 - 14*x^4 + 4*x^5 + 8*x^6) / (1 - 16*x^2 - 3*x^4 + 10*x^6 - 24*x^8 + 16*x^10). - Colin Barker, Sep 23 2018
EXAMPLE
Some solutions for n=4:
..0..x..0..x..0....0..x..2..x..2....0..x..2..x..2....0..x..2..x..2
..x..1..x..1..x....x..1..x..3..x....x..1..x..3..x....x..1..x..3..x
..0..x..2..x..0....2..x..0..x..2....0..x..0..x..2....0..x..0..x..0
..x..1..x..3..x....x..3..x..1..x....x..3..x..3..x....x..3..x..1..x
..0..x..2..x..2....2..x..0..x..0....2..x..2..x..2....0..x..2..x..0
..x..1..x..1..x....x..1..x..3..x....x..1..x..1..x....x..1..x..3..x
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 01 2013
STATUS
approved