OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 30*a(n-1) + 159*a(n-2) - 5480*a(n-3) - 41064*a(n-4) - 53760*a(n-5) - 19600*a(n-6) for n>7.
Empirical g.f.: x*(7 + 690*x + 8199*x^2 + 19736*x^3 - 42600*x^4 + 20160*x^5 + 2800*x^6) / (1 - 15*x - 192*x^2 - 140*x^3)^2. - Colin Barker, Jan 29 2019
EXAMPLE
Some solutions for n=3:
..3..5. .1..6. .3..4. .0..2. .4..6. .1..0. .6..2. .2..5. .1..3. .3..0
..3..2. .0..3. .5..4. .4..1. .4..5. .6..3. .6..2. .3..5. .2..0. .5..3
..1..1. .4..4. .4..1. .3..6. .3..2. .2..2. .5..4. .0..3. .6..5. .2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 08 2016
STATUS
approved