1, 2, 3, 4, 5, 6, 7… How about counting using odd numbers 1, 3, 5, 7, 9… I bet you can can count using even numbers. 2, 4, 6, 8, 10, etc.
But what about reciting all the odd letters of the alphabet?
Or naming all the even letters in order?
It’s pretty hard to do.
Surprisingly, there is very little information online or in books about even and odd letters. Most instances of ACEGIKMOQSUWY are people using it as a username.
This sort of intersection of two systems.