Source code in the icon programming language

procedure hailstone(n)
    while n > 1 do {
        suspend n
        n := if n%2 = 0 then n/2 else 3*n+1
        }
    suspend 1
end


procedure main(args)
    n := integer(!args) | 27
    every writes(" ",hailstone(n))
end


procedure hailstone(n)
    static cache
    initial {
        cache := table()
        cache[1] := [1]
        }
    /cache[n] := [n] ||| hailstone(if n%2 = 0 then n/2 else 3*n+1)
    return cache[n]
end


procedure main(args)
    n := integer(!args) | 27
    task2(n)
    write()
    task3()
end

procedure task2(n)
    count := 0
    every writes(" ",right(!(sequence := hailstone(n)),5)) do
        if (count +:= 1) % 15 = 0 then write()
    write()
    write(*sequence," value",(*sequence=1,"")|"s"," in the sequence.")
end

procedure task3()
    maxHS := 0
    every n := 1 to 100000 do {
        count := *hailstone(n)
        if maxHS <:= count then maxN := n
        }
    write(maxN," has a sequence of ",maxHS," values")
end