OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 42*a(n-1) - 441*a(n-2) for n>3.
Conjectures from Colin Barker, Jan 28 2019: (Start)
G.f.: 6*x*(1 + 38*x + x^2) / (1 - 21*x)^2.
a(n) = 80 * 3^(n-2) * 7^(n-3) * (31*n-20) for n>1.
(End)
EXAMPLE
Some solutions for n=3:
..5..3. .4..0. .0..4. .0..4. .2..3. .5..4. .0..3. .2..5. .4..4. .4..4
..1..4. .1..0. .0..3. .0..5. .5..5. .2..1. .1..4. .4..2. .2..5. .1..2
..3..0. .0..4. .5..3. .4..5. .1..5. .0..0. .5..5. .4..1. .0..0. .2..4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 04 2016
STATUS
approved