Try reading the terms of the sequence aloud, pronouncing the individual digits (as if you were reading out a telephone number): 1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211.... Thus the fourth term would be read as "one-two-one-one." Now note that each term of the sequence describes the preceding term.
Still stumped? You'll just have to send a query to the sequence server.