--global (if you want to be able to call this from test.exw)
function hailstone(atom n)
sequence s = {n}
    while n!=1 do
        if remainder(n,2)=0 then
            n /= 2
        else
            n = 3*n+1
        end if
        s &= n
    end while
    return s
end function

global function hailstone_count(atom n)
integer count = 1
    while n!=1 do
        if remainder(n,2)=0 then
            n /= 2
        else
            n = 3*n+1
        end if
        count += 1
    end while
    return count
end function

if include_file()==1 then

    sequence s = hailstone(27)
    integer ls = length(s)
    s[5..-5] = {".."}
    puts(1,"hailstone(27) = ")
    ? s
    printf(1,"length = %d\n\n",ls)

    integer hmax = 1, imax = 1,count
    for i=2 to 1e5-1 do
        count = hailstone_count(i)
        if count>hmax then
            hmax = count
            imax = i
        end if
    end for

    printf(1,"The longest hailstone sequence under 100,000 is %d with %d elements.\n",{imax,hmax})
end if