OFFSET
1,1
COMMENTS
Column 3 of A207050.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-3) +a(n-4) for n>11.
Empirical g.f.: 3*x*(147 + 184*x + 250*x^2 - 164*x^3 - 185*x^4 - 48*x^5 + 4*x^6 + 48*x^7 + 80*x^8 + 24*x^9 + 2*x^10) / (1 - 4*x^3 - x^4). - Colin Barker, Jun 18 2018
EXAMPLE
Some solutions for n=4:
..0..0..1..1....1..0..2..2....2..1..0..0....2..0..0..2....2..2..0..0
..0..0..0..1....1..1..2..2....2..0..0..0....2..0..0..0....2..0..0..0
..1..0..0..0....1..1..1..2....0..0..0..2....2..2..0..0....0..0..0..2
..1..1..0..0....0..1..1..1....0..0..1..1....2..2..2..0....0..0..1..1
..1..1..1..2....0..0..1..1....1..1..1..1....1..2..2..2....1..1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 14 2012
STATUS
approved