Ahnentafel

An ahnentafel (German for "ancestor table"; ) or ahnenreihe ("ancestor series"; ) is a genealogical numbering system for listing a person's direct ancestors in a fixed sequence of ascent. The subject (proband) of the ahnentafel is listed as #1, the subject's father as #2 and the mother as #3, the paternal grandparents as #4 and #5 and the maternal grandparents as #6 and #7, and so on, back through the generations. Apart from #1, who can be male or female, all even-numbered persons are male, and all odd-numbered persons are female. In this schema, the number of any person's father is double the person's number, and a person's mother is double the person's number plus one. Using this knowledge of numeration, one can derive some basic information about individuals who are listed without additional research.