OFFSET
1,1
COMMENTS
Column 7 of A251894.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 8*a(n-3) - 8*a(n-4) for n>9.
Empirical g.f.: 2*x*(1073 - 482*x + 648*x^2 - 7578*x^3 + 7492*x^4 - 2178*x^5 - 326*x^6 - 3264*x^7 + 4608*x^8) / ((1 - x)*(1 - 2*x)*(1 + 2*x + 4*x^2)). - Colin Barker, Mar 20 2018
EXAMPLE
Some solutions for n=4:
..3..1..0..0..1..0..0..1..3....0..1..0..0..1..0..0..1..0
..1..3..1..1..2..1..1..3..1....1..2..1..1..3..1..1..2..1
..0..1..0..0..1..0..0..1..0....0..1..0..0..1..0..0..1..0
..0..1..0..0..1..0..0..1..0....0..1..0..0..1..0..0..1..0
..1..3..1..1..3..1..1..2..1....1..3..1..1..2..1..1..3..1
..0..1..0..0..1..0..0..1..0....0..1..0..0..1..0..0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 10 2014
STATUS
approved