I immediately see a problem with number $6$, if $1$ is considered non-prime. Are there other numbers that are not possible to write as the sum of $k$ prime numbers?
Note: Prime numbers can be added repeatedly.
I immediately see a problem with number $6$, if $1$ is considered non-prime. Are there other numbers that are not possible to write as the sum of $k$ prime numbers?
Note: Prime numbers can be added repeatedly.
Let $n$ be even. Then $n=\underbrace{2+2+2+\cdots}_{\frac{n}{2} \text{times}}$
Let $n$ be odd. Then $n=\underbrace{2+2+2+\cdots}_{\frac{n-1}{2}-1 \text{ times}}+3$