OFFSET
1,1
COMMENTS
Column 4 of A218810.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) + 15*a(n-2) + 15*a(n-3) + 9*a(n-4) + 9*a(n-5) + 9*a(n-6) + 9*a(n-7).
Empirical g.f.: x*(15 + 24*x + 9*x^2 + 4*x^3 - 3*x^4 + 12*x^5 + 3*x^6) / (1 - 15*x - 15*x^2 - 15*x^3 - 9*x^4 - 9*x^5 - 9*x^6 - 9*x^7). - Colin Barker, Jul 24 2018
EXAMPLE
Some solutions for n=3:
..0..0..1..0....1..0..1..0....1..0..1..0....1..0..0..0....1..0..1..0
..1..1..1..0....1..0..1..0....0..0..0..1....1..0..1..1....0..1..1..0
..1..0..0..0....1..0..0..0....0..1..1..1....0..1..1..0....1..1..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 06 2012
STATUS
approved