The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A249404 Number of ISO 8601 weeks associated with the Gregorian year n. 1
 52, 52, 52, 52, 53, 52, 52, 52, 52, 53, 52, 52, 52, 52, 52, 53, 52, 52, 52, 52, 53, 52, 52, 52, 52, 52, 53, 52, 52, 52, 52, 52, 53, 52, 52, 52, 52, 53, 52, 52, 52, 52, 52, 53, 52, 52, 52, 52, 53, 52, 52, 52, 52, 52, 53, 52, 52, 52, 52, 52, 53, 52, 52, 52, 52, 53, 52, 52, 52 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2000,1 COMMENTS There are 71 ISO 8601 53-week years per 400-year Gregorian cycle. The other years have 52 ISO 8601 weeks. These terms were calculated by using the .NET Framework's Calendar.GetWeekOfYear method with both CalendarWeekRule.FirstFourDayWeek and DayOfWeek.Monday specified for 12/28 of each year (as this date is always in the last week of an ISO 8601-week year). On the Gregorian Calendar, each 400-year cycle includes 97 leap years, giving a total of 400*365 + 97 = 146097 days, which is exactly 20871 weeks; this matches the total number of ISO 8601 weeks per 400-year cycle: 71*53 + (400-71)*52 = 20871. - Jon E. Schoenfield, Oct 30 2014 LINKS Rick L. Shepherd, Table of n, a(n) for n = 2000..2399 Microsoft Developer Network, CalendarWeekRule Enumeration Shawn Steele, ISO 8601 Week of Year Format in Microsoft .Net Wikipedia, ISO week date Wikipedia, Leap week calendar Wikipedia, Seven-day week FORMULA a(n) = a(n - 400) for all n and n - 400 that are defined (proleptic) Gregorian calendar years. EXAMPLE a(2015) = 53 because Gregorian year 2015 has 53 associated ISO 8601 weeks (with week 1 beginning Monday, December 29, 2014). CROSSREFS Cf. A116386. Sequence in context: A126767 A143723 A252713 * A327374 A327109 A327108 Adjacent sequences:  A249401 A249402 A249403 * A249405 A249406 A249407 KEYWORD nonn AUTHOR Rick L. Shepherd, Oct 27 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 17 09:29 EDT 2021. Contains 343064 sequences. (Running on oeis4.)