%I A000924 M0195 N0072
%S A000924 1,1,1,2,2,1,2,1,2,4,2,4,1,4,2,3,6,6,4,3,4,4,2,2,6,4,8,4,1,4,5,2,6,4,4,
%T A000924 2,3,6,8,8,8,1,8,4,7,4,10,8,4,5,4,3,4,10,6,12,2,4,8,8,4,14,4,5,8,6,3,6,
%U A000924 12,8,8,8,2,6,10,10,2,5,12,4,5,4,14,8,8,3,8,4,10,8,16,14,7,8,4,6,8,10
%N A000924 Class number of Q(sqrt(-n)), n square-free.
%D A000924 Z. I. Borevich and I. R. Shafarevich, Number Theory. Academic Press, 
               NY, 1966, pp. 425-430.
%D A000924 D. A. Buell, Binary Quadratic Forms. Springer-Verlag, NY, 1989, pp. 224-241.
%D A000924 R. A. Mollin, Quadratics, CRC Press, 1996, Appendix D, gives a table 
               for n <= 1999, correcting that of Borevich and Shafarevich.
%D A000924 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000924 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A000924 T. D. Noe, <a href="b000924.txt">Table of n, a(n) for n=1..10000</a>
%H A000924 S. R. Finch, <a href="http://algo.inria.fr/bsolve/">Class number theory</
               a>
%H A000924 <a href="Sindx_Qua.html#quadfield">Index entries for sequences related 
               to quadratic fields</a>
%e A000924 a(10)=4, since 14 is the 10-th squarefree number and the class number 
               of Q(sqrt(-14)) is 4.
%Y A000924 Values of n run through A005117. Corresponding discriminants give A033197.
%Y A000924 Sequence in context: A061498 A106029 A105153 this_sequence A109909 A144387 
               A030768
%Y A000924 Adjacent sequences: A000921 A000922 A000923 this_sequence A000925 A000926 
               A000927
%K A000924 nonn,nice,easy
%O A000924 1,4
%A A000924 N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein
%E A000924 Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Mar 17 2003