Question

یکی پس از دیگری

Answer 1

one after another

http://www.macmillandictionary.com/thesaurus-category/british/one-after-another

http://dictionary.cambridge.org/dictionary/english/one-after-another

one after the other

Answer 2

Hi

+ for  Mr. E-Hamzeluyi

You can communicate the meaning by adverbs as well:

Consecutively

Successively

Answer 3

"Subsequent" and "Subsequently" are adjective and adverb forms of the word respectively.