Friday the 13th

Leap years that begin on Sunday (i.e. that follow Dominical Letter AG) such as 2012 and 2040, also have three Friday the 13ths in January, April, and July.

One source mentioned for the unlucky reputation of the number 13 is a Norse myth about twelve gods having a dinner party in Valhalla.

[2][3] The superstition seems to relate to various things, like the story of Jesus's Last Supper and crucifixion in which there were thirteen individuals present in the Upper Room on the thirteenth of Nisan Maundy Thursday, the night before his death on Good Friday.

A character in the 1834 play Les Finesses des Gribouilles states, "I was born on a Friday, December 13th, 1813 from which come all of my misfortunes".

In Hispanic countries, instead of Friday, Tuesday the 13th (martes trece) is considered a day of bad luck.

[16] Tuesday is considered dominated by the influence of Ares, the god of war (or Mars, the Roman equivalent).

By shuffling the digits of the number one can get the Latin vīxī ("I have lived", implying death at present), an omen of bad luck.

[citation needed] According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17–21 million people in the United States are affected by Paraskevidekatriaphobia (fear of Friday the 13th), making it the most feared day and date in history.

Some people are so paralyzed by fear that they avoid their normal routines in doing business, taking flights or even getting out of bed.

[21] In Finland, a consortium of governmental and nongovernmental organizations led by the Ministry of Social Affairs and Health promotes the National Accident Day (kansallinen tapaturmapäivä) to raise awareness about automotive safety, which always falls on a Friday the 13th.

[23] A study by Scanlon, Luben, Scanlon, & Singleton (1993)[24] attracted attention from popular science literature,[c][d] as it concluded that "the risk of hospital admission as a result of a transport accident may be increased by as much as 52 percent on the 13th";[24]: 1584 however, the authors clearly state that "the numbers of admissions from accidents are too small to allow meaningful analysis".

The shortest period that occurs with a Friday the 13th is just one month, from February to March in a common year starting on Thursday (D) (e.g. 2009, 2015 and 2026).