OFFSET
1,1
COMMENTS
Row 2 of A250320.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) - 4*a(n-4) + 2*a(n-5) - a(n-6) + 2*a(n-7) - a(n-8).
Empirical g.f.: x*(8 + 9*x + 18*x^2 + 6*x^3 + 8*x^4 + 2*x^5 + 2*x^6 - x^7) / ((1 - x)^4*(1 + x + x^2)^2). - Colin Barker, Mar 19 2018
EXAMPLE
Some solutions for n=6:
..2....5....6....1....4....1....6....3....3....2....6....0....3....1....0....0
..2....6....1....0....1....3....5....4....4....1....1....0....0....4....3....4
..0....0....6....1....6....3....3....3....0....2....1....2....6....3....1....1
..0....1....1....4....3....5....0....0....1....5....6....6....3....6....4....5
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 18 2014
STATUS
approved