OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - 8*a(n-3) + 6*a(n-4) + 6*a(n-5) - 8*a(n-6) + 3*a(n-8) - a(n-9).
Conjectures from Colin Barker, Nov 05 2018: (Start)
G.f.: x*(48 + 401*x + 669*x^2 + 1241*x^3 - 851*x^4 - 557*x^5 + 7*x^6 + 3*x^7 - x^8) / ((1 - x)^6*(1 + x)^3).
a(n) = 1 + 26*n - 17*n^2 + 24*n^3 + 21*n^4 + n^5 for n even.
a(n) = 39 - n - 36*n^2 + 24*n^3 + 21*n^4 + n^5 for n odd.
(End)
EXAMPLE
Some solutions for n=8:
..3....4....6....3....2....2....5....0....0....3....1....3....2....6....5....1
..1....3....7....8....8....0....1....1....6....2....8....8....6....3....4....5
..2....4....2....5....7....8....5....4....8....4....0....4....1....6....2....3
..6....5....8....3....1....4....7....7....3....5....6....5....5....5....6....8
..3....1....6....1....8....6....1....6....5....4....6....4....2....2....6....0
..2....7....2....2....1....0....4....2....2....1....2....8....6....1....0....8
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 08 2014
STATUS
approved