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A189414 Number of quadrilaterals on an (n X n)-grid (or geoboard). 6


%S 0,1,94,1758,13698,70539,266320,837060,2260984,5460657,12046294,

%T 24775158,47847538,87967579,154764912,262110940,429480216,684015621,

%U 1061192670,1609449754,2390049498,3483126407

%N Number of quadrilaterals on an (n X n)-grid (or geoboard).

%H Weisstein, Eric W.: <a href="http://mathworld.wolfram.com/Quadrilateral.html">MathWorld -- Quadrilateral.</a>

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

%Y Cf. A175383, A189345, A189412, A189413.

%K nonn

%O 1,3

%A _Martin Renner_, Apr 21 2011

%E a(6) - a(22) from _Nathaniel Johnston_, Apr 25 2011

%E a(7) - a(22) corrected by _Michal Forisek_, Sep 06 2011

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Last modified January 17 19:58 EST 2019. Contains 319251 sequences. (Running on oeis4.)