Published online by Cambridge University Press: 11 December 2018
Let $\mathbb{N}$ be the set of all nonnegative integers. For any set
$A\subset \mathbb{N}$, let
$R(A,n)$ denote the number of representations of
$n$ as
$n=a+a^{\prime }$ with
$a,a^{\prime }\in A$. There is no partition
$\mathbb{N}=A\cup B$ such that
$R(A,n)=R(B,n)$ for all sufficiently large integers
$n$. We prove that a partition
$\mathbb{N}=A\cup B$ satisfies
$|R(A,n)-R(B,n)|\leq 1$ for all nonnegative integers
$n$ if and only if, for each nonnegative integer
$m$, exactly one of
$2m+1$ and
$2m$ is in
$A$.
The author is supported by the National Natural Science Foundation of China, Grant No. 11771211.