%I A006683 M0560
%S A006683 1,2,3,4,6,8,11,15,21,28,39,53,99,137,186
%N A006683 Number of regions in certain maps.
%D A006683 Gustavus J. Simmons, The ochromatic number of planar graphs, pp. 295-316 
               of F. Harary and J. S. Maybee, editors, Graphs and Applications. 
               Wiley, NY, 1985.
%D A006683 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%Y A006683 Sequence in context: A087192 A046935 A095814 this_sequence A014213 A064323 
               A003411
%Y A006683 Adjacent sequences: A006680 A006681 A006682 this_sequence A006684 A006685 
               A006686
%K A006683 nonn
%O A006683 1,2
%A A006683 N. J. A. Sloane (njas(AT)research.att.com).