Template:Sequence of the Day for February 29

Intended for: February 29, 2016

Timetable

• First draft entered by Alonso del Arte on March 1, 2011 ✓
• Draft reviewed by Daniel Forgues on February 29, 2016 ✓
• Draft to be approved by January 29, 2016

Yesterday's SOTD * Tomorrow's SOTD

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A090651: Perpetual calendar sequence, for ­

n   ≥   1901

.

{ 3, 4, 5, 13, 1, 2, 3, 11, 6, 7, ... }

There are 14 basic year calendars, 7 for normal years and 7 for leap years. This sequence identifies the calendars for years 1901 through 2099, when it reinitializes because 2100 is not a leap year. Note that ­

a (n) = 1

for years starting on a Sunday, 2 for years starting on a Monday, and so on to 7; 8 for leap years starting on a Sunday, 9 for leap years starting on Monday, and so on to 14. Since this year, 2016, is a leap year—requiring the addition of an extra day, today—starting on a Friday, ­

a (2016) = 13

.