Small Numbers (13)

A number traditionally associated with bad luck. A so-called baker's dozen is equal to 13. Fear of the number 13 is called triskaidekaphobia. There are 13 Archimedean solids. Mazur and Tate (1973/74) proved that there is no elliptic curve over the rationals  having a rational point of order 13.

REFERENCES:

Mazur, B. and Tate, J. "Points of Order 13 on Elliptic Curves." Invent. Math. 22, 41-49, 1973/74.

Wells, D. The Penguin Dictionary of Curious and Interesting Numbers. Middlesex, England: Penguin Books, 1986.