Ahnentafel

An ahnentafel (German for "ancestor table"; German: [ˈʔaːnənˌtaːfəl]) or ahnenreihe ("ancestor series"; German: [ˈʔaːnənˌʁaɪə]) is a genealogical numbering system for listing a person's direct ancestors in a fixed sequence of ascent. The subject (or proband) of the ahnentafel is listed as No. 1, the subject's father as No. 2 and the mother as No. 3, the paternal grandparents as No. 4 and No. 5 and the maternal grandparents as No. 6 and No. 7, and so on, back through the generations. Apart from No. 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 definition of numeration, one can derive some basic information about individuals who are listed without additional research.