A234354 Number of non-equivalent (mod D_3) ways to arrange 6 indistinguishable points on a triangular grid of side n so that no three points are collinear.

1, 47, 1112, 11743, 82988, 433372, 1820163, 6459496, 20287372, 57129426, 147915285, 356109110, 804785159, 1722171831

Offset: 4

Author

Heinrich Ludwig, Dec 30 2013

Keywords

• nonn
• more

Comments

Column 6 of triangle A234350.

Without the restriction "non-equivalent (mod D_3)" the numbers are given by A194134.

Examples

			There is a(4) = 1 non-equivalent way to arrange 6 indistinguishable points (x) on a triangular grid of side 4:
     .
    x x
   x . x
  . x x .
		

Crossrefs

Cf. A234350, A194134

Arranging 3 points: A234351

Arranging 4 points: A234352

Arranging 5 points: A234353

Extensions

a(14)-a(17) from Heinrich Ludwig, Apr 19 2016