OFFSET
1,1
COMMENTS
Column 2 of A252075.
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) - a(n-4) - 4*a(n-5) - 3*a(n-6) + a(n-8) + a(n-9) for n>11.
Empirical g.f.: x*(105 - 58*x + 10*x^2 - 275*x^3 - 163*x^4 + 55*x^5 + 160*x^6 + 77*x^7 + 6*x^8 - 39*x^9 - 4*x^10) / ((1 - x)*(1 - x - 2*x^2 - 6*x^3 - 5*x^4 - x^5 + 2*x^6 + 2*x^7 + x^8)). - Colin Barker, Mar 20 2018
EXAMPLE
Some solutions for n=4:
..2..2..2..2....2..1..2..2....2..2..2..2....2..2..2..1....2..2..2..2
..2..2..1..2....2..2..2..1....2..2..2..2....1..2..2..2....2..1..2..2
..1..2..2..2....2..2..2..2....2..2..2..2....2..2..1..2....2..2..2..2
..2..2..2..2....2..2..2..2....2..1..2..2....2..2..2..2....2..2..2..2
..2..2..2..2....2..2..2..2....2..2..2..2....2..2..2..1....2..2..2..2
..2..1..2..2....1..2..2..1....1..2..2..2....2..2..1..2....2..2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 13 2014
STATUS
approved