OFFSET
1,1
COMMENTS
Column 1 of A223415.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-2) - 12*a(n-4) + 4*a(n-6).
Empirical g.f.: 2*x*(5 + 12*x - 12*x^2 - 20*x^3 + 6*x^4 + 8*x^5) / ((1 - x)*(1 + x)*(1 + 2*x - 2*x^2)*(1 - 2*x - 2*x^2)). - Colin Barker, Aug 20 2018
EXAMPLE
Some solutions for n=3:
..1....7....4....4....8....2....5....4....1....2....4....4....3....4....1....6
..4....4....7....8....4....0....2....2....0....4....8....1....6....2....4....3
..1....8....3....5....7....1....4....0....1....8....4....0....3....5....2....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 20 2013
STATUS
approved