OFFSET
0,4
COMMENTS
Column 3 of A194136.
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 0..500, Mar 20 2016 [First 196 terms from R. H. Hardin]
StackExchange, Number of possible triangles in a given triangle.
FORMULA
a(n) = ((n^2+n+2)/2) * binomial(n+2,4) - (3/2) * Sum_{k=2..n} (n-k+1) * (n-k+2) * Sum_{m=2..k} gcd(k-1,m-1). - David Bevan, Jan 01 2012
EXAMPLE
Some solutions for 3X3X3
....0......1......1......0......1......1......1......0......0......1......0
...1.1....1.0....0.1....1.0....0.0....0.0....1.1....1.1....0.1....0.1....0.1
..0.0.1..0.0.1..1.0.0..1.1.0..0.1.1..1.0.1..0.0.0..0.1.0..1.1.0..0.1.0..1.0.1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 17 2011
STATUS
approved