OFFSET
1,2
COMMENTS
Column 7 of A221573
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 7*a(n-1) +4*a(n-2) +5*a(n-3) +20*a(n-4) +20*a(n-5) +23*a(n-6) -6*a(n-7) +3*a(n-8).
Empirical g.f.: -2*x^2*(25-18*x+51*x^2+4*x^3+66*x^4-18*x^5+6*x^6) / ( -1+7*x+4*x^2+5*x^3+20*x^4+20*x^5+23*x^6-6*x^7+3*x^8 ). - R. J. Mathar, Jun 06 2013
EXAMPLE
Some solutions for n=6
..6....5....1....2....1....3....6....4....4....2....7....0....1....2....2....6
..4....2....6....7....6....6....0....2....0....7....4....4....6....6....4....2
..6....4....7....0....0....1....2....2....7....0....2....1....3....2....1....4
..2....5....4....3....0....4....0....6....4....0....7....1....2....3....6....0
..6....7....3....3....0....7....7....1....0....1....5....6....5....0....6....1
..1....7....1....0....5....0....4....1....0....1....3....0....3....0....0....4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 20 2013
STATUS
approved