Next term is too big to list here. Equivalence is permutation and complementation of n variables on the domain and permutation of 2 variables on the output. [Sean A. Irvine, Jul 12 2011]

REFERENCES

M. A. Harrison, On the number of classes of switching networks, J. Franklin Instit., 276 (1963), 313-327.

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

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