OFFSET
1,3
COMMENTS
Row 9 of A188147.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 5916*n^2 - 38192*n + 55600 for n>7.
Conjectures from Colin Barker, Apr 27 2018: (Start)
G.f.: 4*x^3*(10 + 630*x + 1680*x^2 + 1028*x^3 - 72*x^4 - 240*x^5 - 71*x^6 - 7*x^7) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>10.
(End)
EXAMPLE
Some solutions for 3 X 3:
..3..4..5....1..2..3....3..4..5....9..2..1....3..4..5....9..4..3....7..6..5
..2..7..6....8..7..4....2..9..6....8..3..4....2..1..6....8..5..2....8..3..4
..1..8..9....9..6..5....1..8..7....7..6..5....9..8..7....7..6..1....9..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 22 2011
STATUS
approved