skuddårsekvenser

A skuddårsekvens, or leap year sequence, refers to the predictable pattern of years that occur when leap days are added to the Gregorian calendar. The Gregorian calendar, adopted widely to correct for the inaccuracies of the Julian calendar, institutes a leap year every four years to keep the calendar year synchronized with the astronomical year. However, this rule is modified by exceptions to ensure greater precision.

A year is generally considered a leap year if it is divisible by four. For example, 2020 and 2024 are leap years. This rule, however, has two exceptions. Years that are divisible by 100 are not leap years, unless they are also divisible by 400. Therefore, 1900 was not a leap year, but 2000 was. This century rule means that over a span of 400 years, there are 97 leap years, not 100.

The sequence of leap years and common years therefore follows a recurring pattern. Over a 400-year cycle, the years can be categorized by their divisibility by 4, 100, and 400, determining whether they contain the extra day of February 29th. This meticulous system, while appearing complex, ensures that the calendar remains remarkably accurate over millennia, preventing significant drift between the calendar date and the seasons. Understanding these sequences is crucial for historical dating, astronomical calculations, and any application requiring precise timekeeping.

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