MathDB

Let

n

be a positive integer, and let

A

be a subset of

\{ 1,\cdots ,n\}

. An

A

-partition of

n

into

k

parts is a representation of n as a sum

n = a_1 + \cdots + a_k

, where the parts

a_1 , \cdots , a_k

belong to

A

and are not necessarily distinct. The number of different parts in such a partition is the number of (distinct) elements in the set

\{ a_1 , a_2 , \cdots , a_k \}

. We say that an

A

-partition of

n

into

k

parts is optimal if there is no

A

-partition of

n

into

r

parts with

r<k

. Prove that any optimal

A

-partition of

n

contains at most

\sqrt[3]{6n}

different parts.

C4