A model of cellular automata (CA) is considered to be a well-studied non-linear model of complex systems in which an infinite one-dimensional array of finite state machines (cells) updates itself in a synchronous manner according to a uniform local rule. A sequence generation problem on the CAs has been studied and many scholars proposed several real-time sequence generation algorithms for a variety of non-regular sequences such as prime, Fibonacci, and {2 n | n = 1, 2, 3, . . .} sequences etc. The paper describes the sequence generation powers of CAs having a small number of states, focusing on the CAs with one, two, and three internal states, respectively. The authors enumerate all of the sequences generated by two-state CAs and present several non-regular sequences that can be generated in real-time by three-state CAs, but not generated by any two-state CA. It is shown that there exists a sequence generation gap among the powers of those small CAs.as the authors know, no work, except for this paper, has been done concerning the study of generation powers of CAs with a small number of states.This paper extends the study of Kamikawa and Umeo [12] exhaustively, study sequence generation powers of CAs with a small number of states, and give formal proofs of all algorithms presented. The sequence generation powers of small CAs, focusing on the CAs with one, two, and three internal states is investigeted. The authors enumerate all of the sequences generated by two-state CAs and present several non-regular sequences that can be generated in real-time by three-state CAs, but not generated by any two-state CAs. It is shown that there exists a sequence generation gap among the powers of those small CAs.