OFFSET
1,1
COMMENTS
Column 2 of A219460.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/40320)*n^8 - (1/2016)*n^7 + (7/2880)*n^6 + (53/720)*n^5 - (6313/5760)*n^4 + (1961/288)*n^3 - (170417/10080)*n^2 + (3393/280)*n + 13 for n>5.
Conjectures from Colin Barker, Mar 11 2018: (Start)
G.f.: x*(4 - 32*x + 121*x^2 - 283*x^3 + 459*x^4 - 553*x^5 + 525*x^6 - 411*x^7 + 271*x^8 - 149*x^9 + 71*x^10 - 29*x^11 + 8*x^12 - x^13) / (1 - x)^9.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>14.
(End)
EXAMPLE
Some solutions for n=3:
..1..1....0..0....1..1....2..2....0..0....1..1....2..2....2..2....2..2....0..0
..1..1....0..0....1..1....0..0....0..0....1..1....1..1....2..2....2..2....0..0
..1..1....0..0....3..3....0..0....1..1....2..2....1..1....3..3....2..2....2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 20 2012
STATUS
approved