Editing Leap year starting on Sunday (section)

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A '''leap year starting on Sunday''' is any year with 366 days (i.e. it includes 29 February) that begins on [[Sunday]], 1 January, and ends on [[Monday]], 31 December. Its [[dominical letter]]s hence are '''AG'''. The most recent year of such kind was [[2012]], and the next one will be [[2040]] in the [[Gregorian calendar]]<ref name="math">{{cite web|url=https://webspace.science.uu.nl/~gent0113/calendar/isocalendar.htm |author=Robert van Gent |title=The Mathematics of the ISO 8601 Calendar |publisher=Utrecht University, Department of Mathematics |date=2017 |access-date=20 July 2017}}</ref> or, likewise [[2024]] and 2052 in the obsolete [[Julian calendar]].

This is the only leap year with three occurrences of [[Friday the 13th]]: those three in this leap year occur three months (13 weeks) apart: [[January 13|in January]], [[April 13|April]], and [[July 13|July]]. [[Common year starting on Thursday|Common years starting on Thursday]] share this characteristic, in the months of February, March, and November.

Additionally, these types of years are the only ones which contain 54 different calendar weeks (2 partial, 52 in full) in areas of the world where Monday is considered the first day of the week.

This year has five months (January, April, July, September and December) which begin on a weekend-day. This is the greatest possible number of months to begin on a weekend-day in a given year; this is the only kind of year in which this occurs.