OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-2) + 2*a(n-3) - 3*a(n-4) - 6*a(n-5) + 6*a(n-7) + 3*a(n-8) - 2*a(n-9) - 3*a(n-10) + a(n-12).
Empirical for n mod 6 = 0: a(n) = (175/72)*n^4 - (40/9)*n^3 + (115/6)*n^2 - (32/3)*n + 1
Empirical for n mod 6 = 1: a(n) = (175/72)*n^4 - (40/9)*n^3 + (185/12)*n^2 - (41/9)*n - (493/72)
Empirical for n mod 6 = 2: a(n) = (175/72)*n^4 - (40/9)*n^3 + (115/6)*n^2 - (136/9)*n + (29/9)
Empirical for n mod 6 = 3: a(n) = (175/72)*n^4 - (40/9)*n^3 + (185/12)*n^2 + (13/3)*n - (197/8)
Empirical for n mod 6 = 4: a(n) = (175/72)*n^4 - (40/9)*n^3 + (115/6)*n^2 - (176/9)*n + (169/9)
Empirical for n mod 6 = 5: a(n) = (175/72)*n^4 - (40/9)*n^3 + (185/12)*n^2 - (1/9)*n - (1613/72).
Empirical g.f.: x*(2 + 53*x + 198*x^2 + 422*x^3 + 614*x^4 + 825*x^5 + 810*x^6 + 653*x^7 + 416*x^8 + 206*x^9 + x^11) / ((1 - x)^5*(1 + x)^3*(1 + x + x^2)^2). - Colin Barker, Nov 09 2018
EXAMPLE
Some solutions for n=6:
..3....1....0....3....6....5....5....6....0....6....3....6....6....2....4....2
..4....2....2....0....5....2....3....6....4....3....1....6....1....1....5....2
..0....0....0....6....2....1....5....5....0....6....6....1....0....4....3....1
..2....1....4....6....6....2....6....1....5....3....5....2....6....3....2....5
..6....1....4....0....1....0....1....2....1....2....0....0....2....0....6....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 18 2014
STATUS
approved