OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/5040)*n^7 + (1/240)*n^6 + (13/720)*n^5 + (5/48)*n^4 + (119/90)*n^3 - (73/120)*n^2 - (2873/420)*n + 23 for n>3.
Conjectures from Colin Barker, Sep 07 2018: (Start)
G.f.: x*(4 - 17*x + 40*x^2 - 52*x^3 + 37*x^4 - 11*x^5 + 2*x^6 - 3*x^7 - x^8 + 3*x^9 - x^10) / (1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>11.
(End)
EXAMPLE
Some solutions for n=4:
..0..1....0..0....0..0....0..1....0..0....1..0....0..1....0..1....0..0....1..0
..1..1....0..1....1..0....1..0....0..0....1..1....0..0....0..0....1..0....1..1
..0..1....1..1....1..1....0..1....0..1....1..1....1..0....1..0....1..1....1..0
..0..1....0..1....1..0....0..0....0..0....1..1....1..0....0..0....0..0....1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 01 2013
STATUS
approved