Some cryptographic algorithm requires matching natural numbers that can be represented as a sum of two different prime numbers using more than k ways, thus all the three numbers (the unknown and two summands) should have the same number of digits. For example: number 30 matches k-1 case as it can be represented as follows:
![](https://st.testna5.ru/images/22c/22cf93d1ef72b91b156948875f5115d5.png)
and
![](https://st.testna5.ru/images/415/415445243720e78974b3d9e8ff62ed09.png)
. Number 32 doesn’t match as it can be represented by only one sum: 19+13.
The quantity of 4-digit decimals for k= 10 is …