Block-Structured Prime Magic Squares: Orders 15 to 23

This work bring different ways of representing prime magic squares. These are of type: blocks, block-bordered, concentric, nested, etc. This work is for the orders 15 to 23 with prime number entries. For previous work from orders 6 to 14 see the reference list. There are magic squares such as of orders 17, 19, 22, 23, etc. These are either prime number orders or double-prime number orders. There is a difficulty in representing them in equal sums blocks. In case of orders 22, we are able bring blocks of equal sums of order 11 with prime numbers. In case of 17, 19 and 23, a little different approach is applied. For these types of magic squares, an external borders are considered, and the internal part is represented in terms of blocks, for example, in case of orders 17, 19 and 23, blocks of order 15 and 21 are applied in the inner parts.