IMO Shortlist 1987 problem 14
Dodao/la:
arhiva2. travnja 2012. How many words with
![n](/media/m/a/e/5/ae594d7d1e46f4b979494cf8a815232b.png)
digits can be formed from the alphabet
![\{0, 1, 2, 3, 4\}](/media/m/6/3/a/63aae8591794b7503b7b07a9310997ee.png)
, if neighboring digits must differ by exactly one?
Proposed by Germany, FR.
%V0
How many words with $n$ digits can be formed from the alphabet $\{0, 1, 2, 3, 4\}$, if neighboring digits must differ by exactly one?
Proposed by Germany, FR.
Izvor: Međunarodna matematička olimpijada, shortlist 1987