what does this notation mean:
where $\chi(D)$ - character of the group ring. D - element of the group of ring, p - prime number.
It is looks like a greatest common divisor, but it is not.
I found this notation in the book Addition theorems, H. B. MANN, 1965. https://www.amazon.com/Addition-Theorems-H-B-Mann/dp/047056735X without explanation: