OFFSET
2,2
COMMENTS
EXAMPLE
There are a(3) = 5 non-equivalent ways to arrange 3 indistinguishable points (x) on a triangular grid of side 3:
x . x x x
. . x x x x . . x .
x . x . x . . . . . x x . x .
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Heinrich Ludwig, Dec 30 2013
EXTENSIONS
a(14)-a(17) from Heinrich Ludwig, Apr 19 2016
STATUS
approved