Pope John (numbering) in Encyclopedia

There has been much confusion of the numbering of Popes John, due to the legend of another pope John between John XIV and John XV, and the antipapacy of John XVI. The sequence of Johns is now two off.

John	Dates of Papacy	Né	Notes	#
There is no controversy regarding the numbering of the popes John before XV I II III IV V VI VII Anti-VIII VIII IX X XI XII XIII
Pope John XIV	983–984	Pietro Canepanova		14
John			Medieval historians misreading the Liber Pontificalis assumed another Pope John between Pope John XIV and the true Pope John XV, mistaking him with the historical character of cardinal deacon John son of Robert, that opposed to Antipope Boniface VII.	–
Pope John XV	985–996	John	sometimes called XVI because of legendary predecessor, born to confusion between the reign of Boniface VII, the four month-long imprisonment of John XIV signed as a distinct pontificate in the Liber Pontificalis and the historical cardinal deacon John son of Robert that opposed to Boniface VII after death of John XIV	15
Antipope John XVI	997–998	Johannes Philagathos or Piligato or Filagatto	An antipope, according to conventional wisdom, and thus his regnal number XVI should have been reused. This occurred, but some centuries later the sequencing was wrongly "corrected" by some medieval historians and it has never been corrected again. He was elected in opposition to Pope Gregory V (996?999).	–
Pope John XVII	1003	Sicco	Took the number XVI, but some historians corrected his number in XVII despite XVI having been an antipope. Sometimes called John XVII (XVIII) due to legend of another John between XIV & XV.	16
Pope John XVIII	1004–1009	Fasanius	He took the number XVII, but some historians corrected his number to include Antipope John XVI. Sometimes called John XVIII (XIX) due to legend of another John between XIV & XV.	17
Pope John XIX	1024–1032	Romanus	He took the number XVIII, but some historians corrected his number to include Antipope John XVI.	18
Pope John XX			There has never been a Pope John XX because Pedro Julião on election decided to skip the number XX and to be counted as John XXI instead. He wanted to correct what in his time was believed to be an error in the counting of his predecessors John XV – XIX.	–
Pope John XXI	1276–1277	Pedro Julião romanised as Petrus Hispanus		19
Pope John XXII	1316–1334	Jacques Duèze		20
Antipope John XXIII	1410–1415	Baldassare Cossa		–
Pope John XXIII	1958–1963	Angelo Giuseppe Roncalli	Roncalli's choice of XXIII rather than XXIV confirmed the antipope status of Antipope John XXIII.	21