OFFSET
1,1
COMMENTS
Column 7 of A217883.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + 3*a(n-8) - a(n-9) + a(n-10) + a(n-11) + a(n-12) + a(n-13) + a(n-14) + a(n-15).
Empirical g.f.: x*(1 + x^2 + x^3 + x^4 + x^5 + x^6 + x^7)*(3 + x^2 + x^3 + x^4 + x^5 + x^6 + x^7) / ((1 - x + x^4 + x^5 + x^6 + x^7)*(1 - 2*x + x^2 - x^4 - x^8)). - Colin Barker, Jul 23 2018
EXAMPLE
Some solutions for n=4:
..0....0....0....0....0....0....0....0....0....2....0....2....0....1....0....0
..0....2....0....1....0....1....0....0....1....2....2....2....0....2....1....0
..1....1....2....2....2....2....1....1....1....2....2....2....0....2....1....2
..2....1....2....0....0....2....0....1....0....2....0....0....0....2....2....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 14 2012
STATUS
approved