S. Louboutin, COMPUTATION OF THE RELATIVE CLASS-NUMBERS OF SOME HILBERT CLASS FIELDS, Comptes rendus de l'Academie des sciences. Serie 1, Mathematique, 319(4), 1994, pp. 321-325
We give an expression for the relative class number of any CM-field th
at is suitable for numerical computation. This expression is then used
in order to compute relative class numbers of 2-narrow Hilbert class
fields of real quadratic fields for which their 2-Sylow subgroups of t
heir ideal class groups are cyclic. These computations suggest that th
ere are exactly 24 such 2-narrow Hilbert class fields with relative cl
ass number one, and that they have degree 8 or 16.