2,2

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Rosenberg, Ivo; The number of maximal closed classes in the set of functions over a finite domain. J. Combinatorial Theory Ser. A 14 (1973), 1-7.

Zaharova, E. Ju.; Kudrjavcev, V. B.; Jablonskii, S. V.; Precomplete classes in $k$-valued logics. (Russian) Dokl. Akad. Nauk SSSR 186 (1969), 509-512. English translation in Soviet Math. Doklady 10 (No. 3, 1969), 618-622.

Sequence in context: A084879 A141118 A033030 this_sequence A160707 A135077 A157538

Adjacent sequences: A002821 A002822 A002823 this_sequence A002825 A002826 A002827

nonn

N. J. A. Sloane (njas(AT)research.att.com).