clg

graphsize 500,500

color yellow

rect 0,0,500,500

color black

f=0

for h = 3 to 10000

if f=0 then

Prime = h-1

y = int(Prime/100)

x = Prime - y*100 -1

Rect 5*x,5*y,5,5

print Prime

end if

f=0

for i = 2 to int(h/2)+1 step 1

if int(h/i)=h/i then f=1

if int(h/i)=h/i then i=h/2

next i

next h

FYI... when checking for prime you only need to check factors up to the square root of the test number.

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