OFFSET
1,6
COMMENTS
Row 7 of A187172.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 780*n^2 - 9880*n + 29384 for n>11.
G.f.: 4*x^6*(4 + 80*x + 136*x^2 + 143*x^3 + 85*x^4 + 19*x^5 - 43*x^6 - 29*x^7 - 5*x^8) / (1 - x)^3 (conjectured). - Colin Barker, Apr 22 2018
EXAMPLE
Some solutions for 6 X 6:
..0..0..3..0..0..0....0..1..0..0..0..0....0..0..0..6..0..0....0..0..0..4..0..0
..4..0..0..0..0..1....0..0..0..0..7..0....0..7..0..0..0..0....0..5..0..0..0..0
..0..0..0..2..0..0....0..0..2..0..0..0....0..0..0..0..5..0....0..0..0..0..3..0
..0..5..0..0..0..0....3..0..0..0..0..6....0..0..2..0..0..0....0..0..6..0..0..0
..0..0..0..0..7..0....0..0..0..5..0..0....1..0..0..0..0..4....7..0..0..0..0..2
..0..0..6..0..0..0....0..4..0..0..0..0....0..0..0..3..0..0....0..0..0..1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 06 2011
STATUS
approved