Question 107725
I just drew up the whole thing. 75 events can be shown as 15 groups 
of 5 each (75 = 15*5). I wanted to see if the robots and vampires
would try to come at the same time
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1  2  3  4  5  6  7  8  9  0  I  2  3  4  5
V  1  1  R  V  1  1  1  V  R  1  1  V  1  1 
2  2  2  V  R  2  2  V  2  2  R  V  2  2  2
3  3  V  3  3  R  V  3  3  3  V  R  3  3  V
R  V  4  4  4  V  R  4  4  V  4  4  R  V  4 
V  R  5  5  V  5  5  R  V  5  5  5  V  R  5
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There are 15 groups of 5 each. Every 4th is a Vampire. Every 6th is
a Robot. If you look at the patterns of R's and V's they arediagonals
going in opposite directions, so a V & R can never end up in the same
position. Counting V's I get 19. Counting R's I get 12