%I A006984 M2298
%S A006984 1,1,3,4,3,4,7,7,9,7,7,12,13,12,13,16,13,13,19,16,21,19,19,21,25,21,27,
%T A006984 28,21,27,31,28,27,28,31,36,37,31,39,37,37,36,43,39,39,39,39,48,49,43,
               43
%N A006984 Greatest minimal norm of sublattice of index n in hexagonal lattice.
%C A006984 The hexagonal lattice is the familiar 2-dimensional lattice in which 
               each point has 6 neighbors. This is sometimes called the triangular 
               lattice.
%D A006984 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A006984 M. Bernstein, N. J. A. Sloane and P. E. Wright, On Sublattices of the 
               Hexagonal Lattice, Discrete Math. 170 (1997) 29-39 (<a href="http:/
               /www.research.att.com/~njas/doc/paul.txt">Abstract</a>, <a href="http:/
               /www.research.att.com/~njas/doc/paul.pdf">pdf</a>, <a href="http:/
               /www.research.att.com/~njas/doc/paul.ps">ps</a>).
%H A006984 G. Nebe and N. J. A. Sloane, <a href="http://www.research.att.com/~njas/
               lattices/A2.html">Home page for hexagonal (or triangular) lattice 
               A2</a>
%Y A006984 Cf. A003051, A003050, A001615.
%Y A006984 Sequence in context: A061988 A094151 A135800 this_sequence A087275 A072942 
               A025267
%Y A006984 Adjacent sequences: A006981 A006982 A006983 this_sequence A006985 A006986 
               A006987
%K A006984 nonn,nice
%O A006984 1,3
%A A006984 N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)