如何使用一些文本处理（awk等..）将某些字符放在某些行的文本文件中

I have a text file which has hex values, one value on one separate line. A file has many such values one below another. I need to do some analysis of the values for which i need to but some kind of delimiter/marker say a '#' in this file before line numbers 32,47,62,77... difference between two line numbers in this patterin is 15 always.I have a text file which has hex values, one va