OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/8064)*n^8 + (1/288)*n^7 + (103/2880)*n^6 + (17/90)*n^5 + (703/1152)*n^4 + (451/288)*n^3 + (2869/3360)*n^2 + (209/120)*n + 2.
Conjectures from Colin Barker, Dec 06 2018: (Start)
G.f.: x*(7 - 23*x + 79*x^2 - 147*x^3 + 176*x^4 - 138*x^5 + 67*x^6 - 18*x^7 + 2*x^8) / (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>9.
(End)
EXAMPLE
Some solutions for n=4:
..0..0..1..2....0..1..1..1....0..1..2..3....0..0..1..2....0..0..1..1
..1..1..2..3....0..1..1..2....1..2..3..3....1..1..1..2....1..1..1..2
..1..1..2..3....1..2..2..3....1..2..3..3....2..2..2..3....1..2..2..3
..1..2..3..4....1..2..3..4....2..3..3..4....2..3..3..4....1..2..3..4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 22 2014
STATUS
approved