OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/40)*n^5 + (7/8)*n^3 + (21/10)*n + 1.
Conjectures from Colin Barker, Sep 06 2018: (Start)
G.f.: x*(4 - 11*x + 19*x^2 - 16*x^3 + 8*x^4 - x^5) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..0....0..0...-1..0....0..0...-1..1...-1..0....0.-1....0.-1
..0.-1....0.-1....0..0....0..0....0..0....0.-1....1.-1....1..0....0..0...-1..0
..0..0....0..1....0.-1...-1..1....1..0...-1..0....0..0....0..0....0..1....0..0
.-1..0...-1.-1...-1.-1....0..0....0..0....1..0....0..0....0..0...-1.-1....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Jun 20 2013
STATUS
approved