N rays can form several angles from a point.
n 2 3 4 5 6 7 8
a 1 36 1 1 5 2 1 28
Just write the rules
a(n)=a(n- 1)+n- 1
a(n)=n(n- 1)/2
That is, when n straight lines intersect at a point, n(n- 1)/2 antipodal angles can be formed.