OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) -a(n-2) +4*a(n-3) -2*a(n-6) -4*a(n-7) +2*a(n-9) for n>10.
Empirical g.f.: x*(33 + 2*x + 51*x^2 - 20*x^3 - 24*x^4 - 56*x^5 - 66*x^6 + 12*x^7 + 36*x^8 + 2*x^9) / ((1 - x)*(1 - x - 4*x^3 - 4*x^4 - 4*x^5 - 2*x^6 + 2*x^7 + 2*x^8)). - Colin Barker, Dec 20 2018
EXAMPLE
Some solutions for n=4:
..1..0..1....0..1..1....0..1..1....1..1..0....0..1..1....1..1..1....1..1..1
..1..1..1....1..1..0....1..1..1....1..1..1....1..1..1....1..0..1....1..1..1
..1..1..0....1..1..1....1..0..1....1..1..1....1..1..1....1..1..1....1..0..1
..0..1..1....1..1..1....1..1..1....1..1..0....0..1..1....1..1..0....1..1..1
..1..1..1....0..1..1....1..1..1....0..1..1....1..1..1....0..1..1....0..1..1
..1..0..1....1..1..1....1..0..1....1..1..1....1..0..1....1..0..1....1..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 13 2015
STATUS
approved