OFFSET
1,1
COMMENTS
Column 4 of A219502.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/6)*n^3 + 1*n^2 + (23/6)*n - 7 for n>2.
Conjectures from Colin Barker, Jul 26 2018: (Start)
G.f.: x*(4 - 9*x + 14*x^2 - 11*x^3 + 2*x^4 + x^5) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>6.
(End)
EXAMPLE
Some solutions for n=3:
..0..0..0..0....1..1..0..0....0..0..0..0....1..0..0..0....1..1..0..0
..1..0..0..0....1..1..1..0....1..0..0..0....1..0..0..0....1..1..0..0
..1..0..0..0....1..1..1..1....1..1..1..0....1..0..0..0....1..1..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 20 2012
STATUS
approved