OFFSET
1,1
COMMENTS
Column 3 of A219704.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/24)*n^4 + (1/12)*n^3 - (25/24)*n^2 + (107/12)*n - 10 for n>1.
Conjectures from Colin Barker, Jul 27 2018: (Start)
G.f.: x*(3 - 10*x + 18*x^2 - 20*x^3 + 15*x^4 - 5*x^5) / (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>6.
(End)
EXAMPLE
Some solutions for n=3:
..0..0..0....0..0..0....0..0..1....0..0..0....0..0..0....0..0..0....0..0..0
..0..0..0....0..0..1....0..0..1....0..0..0....0..0..1....0..0..0....0..0..0
..0..1..1....0..1..1....0..0..1....0..0..1....1..1..1....0..0..0....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 25 2012
STATUS
approved