OFFSET
1,1
COMMENTS
Column 4 of A207068.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (3/4)*n^4 + (15/2)*n^3 + (15/4)*n^2 - 3*n.
Conjectures from Colin Barker, Jun 18 2018: (Start)
G.f.: 9*x*(1 + 4*x - 3*x^2) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.
(End)
EXAMPLE
Some solutions for n=4:
..1..0..0..0....0..0..0..0....1..1..1..1....1..1..0..0....0..0..0..0
..1..0..0..0....0..1..1..1....1..1..1..1....1..0..0..0....0..1..1..0
..1..0..0..0....0..1..1..0....1..1..1..1....0..0..0..0....0..1..1..0
..0..0..0..0....0..1..1..0....1..1..1..1....0..0..0..0....0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 14 2012
STATUS
approved