A189414 Number of quadrilaterals on an n X n grid (or geoboard).

0, 1, 94, 1758, 13698, 70539, 266320, 837060, 2260984, 5460657, 12046294, 24775158, 47847538, 87967579, 154764912, 262110940, 429480216, 684015621, 1061192670, 1609449754, 2390049498, 3483126407

Offset: 1

Author

Martin Renner, Apr 21 2011

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Quadrilateral.

Crossrefs

Cf. A175383, A189345, A189412, A189413.

Formula

a(n) = A189412(n) + A189413(n).

Extensions

a(6) - a(22) from Nathaniel Johnston, Apr 25 2011

a(7) - a(22) corrected by Michal Forisek, Sep 06 2011