Data from extensive computations on class groups of quadratic imaginary fields is available below. It is organized by fundamental discriminant $-d$, and divided into four groups based on congruences:

For each congruence class above, there are 4096 files, indexed from $k=0$ to $k=4095$. The $k$th file contains data for $k\cdot 2^{28} \leq |d| \lt (k+1)\cdot 2^{28}$. The files are named accordingly, so the $k=12$ file for $d\equiv 7\pmod8$ is called cl7mod8.12.gz, the final extension because it has been compressed with gzip. The compressed files range in size from 50 to 200 megabytes.

After uncompressing with gzip, files have the following format:

Getting files

$d \equiv $
$k = $ integer from 0 to 4095