I can't understand the task. What did the teacher mean?

Question

Programming

Hello!
I am a first-year student of the specialty "Software Engineering", received this assignment:

Tell me, please, what did the author of the assignment mean?
I generated an array of prime numbers in binary representation using the Eratosthenes algorithm, looked through it with my eyes, looked for symmetry like "111000" or "1010", as a result I can say that there are no symmetrical ones among them, except for the number 2 ("10" in binary system) . He also wrote code, ran it through the array up to a million prime numbers, and caught only two.
There is simply nothing like "111000" or "10101010" there.
Perhaps some other symmetry is meant here?
Please help, I'm breaking my head..

Answer 1

Symmetry is probably 10|01 or 101|101.