MathDB

Binary sequences!

Source: Bulgaria 1998 Problem 1

January 25, 2015

combinatorics unsolvedcombinatorics

Problem Statement

Let

n

be a natural number. Find the least natural number

k

for which there exist

k

sequences of

0

and

1

of length

2n+2

with the following property: any sequence of

0

and

1

of length

2n+2

coincides with some of these

k

sequences in at least

n+2

positions.