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