Wikipedia:Reference desk/Archives/Mathematics/2020 January 1

= January 1 =

When are class numbers of imaginary quadratic fields with discriminant 1-4*n odd?
I'm looking at class numbers for quadratic fields with discriminant -q where q has the form 4*n-1; see. This seems to be always odd when q is prime, and only odd when q has the form p2k+1 where p is prime. Is this relatively obvious? I can't seem to find anything on it with Google. --RDBury (talk) 10:13, 1 January 2020 (UTC)