fprim := proc(n :: nonnegint)
local i;
if ( n=1)
then return(false)
fi;
for i from 2 to floor(sqrt(n)) do
if (n mod i) = 0
then return(false)
fi
od;
return true;
end:

p:= 3001 : counter := 0:

for n from 1 to 3001 do
if (fprim(n) = true)
then m := (p-n);
if ((m mod 3) = 0)
then
counter := counter +1;
fi
fi
od;
counter;