Gleichniszahlenreihe
Gleichniszahlenreihe, or the look-and-say sequence, is constructed from an aural description of a sequence of numbers.
Consider the sequence of numbers that begins with `1, 11, 21, 1211, 111221, 312211, 13112221, ...`. Each number in the sequence represents what would result if the digits in the preceding value were counted and spoken aloud. For instance, "1" yields "one 1 → 11"; "11" yields "two 1s → 21"; "21" yields "one 2, one 1 → 1211", and so forth. The next number in the sequence after "13112221" is thus "one 1, one 3, two 1s, three 2s, one 1 → 1113213211".
This is a fairly complicated program. You need a few parts: the ability to take a tape and parse it into components, the ability to count components, and the ability to produce a new tape. Then a recursing bit to produce a list of these values and (ultimately) return the last one. Think about the Caesar cipher's structure.
