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%I #7 Mar 23 2013 15:10:04
%S 1,4,10,18,35,64,117,190,330,492,780,1050,1605,2080,2941
%N Number of regions in the exterior of a regular n-gon with all diagonals drawn.
%e a(3) = 1 since the equilateral triangle has no diagonals and therefore one exterior region (with infinite area).
%e a(4) = 4 since the two diagonals of the square divide the exterior in four regions (with infinite area).
%e a(5) = 10 since the ten diagonals of the regular pentagon divide the exterior in ten regions (with infinite area) of two different shapes.
%Y Cf. A007678.
%K nonn
%O 3,2
%A _Martin Renner_, Mar 23 2013
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