MathDB

6

Part of 1995 Swedish Mathematical Competition

Problems(1)

signals used for communication are binary sequences of length 10

Source: 1995 Swedish Mathematical Competition p6

4/2/2021
Signals used for communication are binary sequences of length 1010. Unfortunately, the receiving device got broken so that it cannot distinguish between two signals unless those differ in more than five places. What is the largest possible number of signals that can still be used to prevent ambiguities?
combinatorics