OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 3*a(n-3) - 13*a(n-4) + 8*a(n-5) + 70*a(n-6) - 105*a(n-7) + 42*a(n-8) for n>10.
Empirical g.f.: x*(223 - 737*x + 85*x^2 + 386*x^3 + 2981*x^4 + 91*x^5 - 14137*x^6 + 16334*x^7 - 4830*x^8 - 420*x^9) / ((1 - x)^2*(1 - 2*x)*(1 - 3*x^2)*(1 - 7*x^3)). - Colin Barker, Dec 07 2018
EXAMPLE
Some solutions for n=2:
..0..1..1..2..2....0..1..1..2..2....0..1..1..0..1....0..1..1..2..2
..3..0..0..1..1....3..0..0..4..4....0..2..0..0..2....3..0..0..1..1
..2..4..4..0..4....2..3..3..1..1....0..0..2..0..0....2..3..3..0..0
..1..3..3..4..3....4..2..2..0..0....0..1..1..0..1....1..4..4..3..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 25 2014
STATUS
approved