OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 12*a(n-1) - 60*a(n-2) + 162*a(n-3) - 255*a(n-4) + 234*a(n-5) - 116*a(n-6) + 24*a(n-7) for n>9.
Conjectures from Colin Barker, Nov 23 2018: (Start)
G.f.: x*(403 - 3511*x + 12668*x^2 - 24246*x^3 + 25568*x^4 - 13314*x^5 + 1284*x^6 + 1746*x^7 - 594*x^8) / ((1 - x)^3*(1 - 2*x)^3*(1 - 3*x)).
a(n) = (-8*(179+223*2^n-25*3^(3+n)) + (1104-845*2^n)*n + (32+375*2^n)*n^2) / 32 for n>2.
(End)
EXAMPLE
Some solutions for n=4:
..1..2..1..1....1..1..0..0....2..1..0..1....2..2..1..0....2..0..1..0
..0..1..0..0....1..2..1..1....1..2..1..2....2..2..2..1....2..0..1..2
..1..2..1..2....1..2..1..1....1..2..1..2....1..1..1..0....2..0..1..2
..1..2..1..2....0..1..0..0....1..2..1..2....1..1..1..1....2..0..1..2
..0..1..0..1....0..2..2..2....1..2..1..2....1..1..1..2....2..0..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 28 2014
STATUS
approved