The Willmann Tables
Combinations of type A: Up to five resistors in series or capacitors in parallel.
Combinations of type B: Up to five resistors in parallel.
Combinations of type C: One resistor in series with two in parallel. Applies only to three-resistor combinations.
Combinations of type D: One resistor in parallel with two in series. Applies only to three-resistor combinations.
More detailed information is given in the read-me files. The tables are grouped in zip files dealing with the component series E6, E12, E24, E48, and E96.
Be aware that the text files are Unix plain text files that should open seamlessly on Unix systems but will not open properly in Notepad, due to an issue with the Unix-style line breaks. They open nicely in Wordpad, Word, or NoteTab under Windows. This is Microsoft's fault, not Gert's.