TITLE: How do you read "$a_n$" in English?
QUESTION [11 upvotes]: What is the correct way to read "$a_n$" in English? What is the translation of what in Spanish is "$a$ sub $n$"?

REPLY [11 votes]: Believe it or not, the usual way is ‘$a$ sub $n$’.

REPLY [11 votes]: I've always read it as "a sub n."