OFFSET
1,1
COMMENTS
Column 3 of A223838.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (2/3)*n^3 + (3/2)*n^2 + (35/6)*n - 1.
Conjectures from Colin Barker, Aug 23 2018: (Start)
G.f.: x*(7 - 6*x + 2*x^2 + x^3) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.
(End)
EXAMPLE
Some solutions for n=3:
..0..1..0....1..1..0....1..1..1....1..0..0....0..0..1....1..0..0....0..1..0
..0..1..0....1..1..1....1..1..1....1..0..0....0..1..1....1..1..1....1..1..0
..1..1..0....1..1..1....1..1..1....1..0..0....1..1..1....1..1..1....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 27 2013
STATUS
approved