function semiprime(integer n)
    sequence f = prime_factors(n)
    integer l = length(f)
    return (l=2 and n=f[1]*f[2]) or (l=1 and n=power(f[1],2))
end function

procedure test(integer start, integer stop)
sequence s = {}
    for i=start to stop do
        if semiprime(i) then
            s &= i
        end if
    end for
    ?s
    ?length(s)
end procedure
test(1,100)
test(1675,1680)