OFFSET
1,1
COMMENTS
Column 3 of A219403.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 3*a(n-3) + 4*a(n-4) + 2*a(n-5) - 5*a(n-6) - 2*a(n-7) for n>8.
Empirical g.f.: x*(4 - 8*x + 12*x^2 - 9*x^3 - 3*x^4 - 7*x^5 + 7*x^6 + 2*x^7) / (1 - 3*x + 2*x^2 - 3*x^3 - 4*x^4 - 2*x^5 + 5*x^6 + 2*x^7). - Colin Barker, Mar 11 2018
EXAMPLE
Some solutions for n=3:
..1..1..1....1..1..1....1..0..0....0..0..0....1..1..1....1..0..0....0..0..1
..0..0..0....1..1..1....1..0..0....0..0..0....1..0..0....0..0..0....0..0..1
..0..0..0....1..1..1....1..1..1....1..1..1....1..0..0....0..0..0....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 19 2012
STATUS
approved