OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) + 13*a(n-2) - 134*a(n-3) + a(n-4) + 480*a(n-5) - 224*a(n-6) - 96*a(n-7).
Empirical g.f.: 2*x*(91 + 13*x - 1461*x^2 + 479*x^3 + 5523*x^4 - 2943*x^5 - 1197*x^6) / (1 - 9*x - 13*x^2 + 134*x^3 - x^4 - 480*x^5 + 224*x^6 + 96*x^7). - Colin Barker, Oct 16 2018
EXAMPLE
Some solutions for n=4:
..4..1....4..3....0..4....4..1....4..1....0..1....4..0....1..3....2..0....3..0
..4..0....1..4....0..4....2..3....0..0....1..4....0..0....2..0....2..4....4..0
..4..0....0..1....1..3....0..4....2..4....0..3....4..3....3..4....0..1....4..1
..3..0....1..4....3..1....1..3....0..4....4..4....2..0....3..0....4..1....4..0
..2..3....0..3....1..3....4..2....1..1....2..0....4..1....4..0....3..0....3..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 02 2014
STATUS
approved