%I M0152 #11 Jan 27 2014 08:54:41
%S 1,1,1,2,1,3,3,2,4,1,5,2,4,3,1,7,5,3,6,2,8,5,3,8,2,10,2,5,5,3,10,7,4,
%T 10,1,11,5,8,2,13,4,9,4,3,14,4,7,5,12,2,15,6,7,12,4,13,2,11,3,14,4,8,
%U 8,10,3,19,10,4
%N Class number of quadratic field with discriminant -4n+1.
%D D. A. Buell, Binary Quadratic Forms. Springer-Verlag, NY, 1989, pp. 224-241.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%Y Cf. A006643.
%K nonn
%O 1,4
%A _N. J. A. Sloane_, _Mira Bernstein_