Name of a number!
Positive integers are the simplest to conceive, they are even called 'natural'. Yet they contain rich and surprising properties. Some of them bear the name of the person who studied them, or even, one might say, discovered them. Whether they answer a counting question, possess remarkable arithmetic properties, or denote orders of magnitude that are difficult to conceive, encountering some of these 'numbers named after…' is an opportunity to explore the history of mathematics.
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Sophie Germain primes | Tangente
From Fermat's Last Theorem to cryptography, Sophie Germain primes have played a part in many scientific adventures over the past two centuries. These prime numbers have earned their place in the pantheon of arithmetic, yet we still do not know whether infinitely many exist.
Catalan numbers
Eugène Charles Catalan (1814–1894), the son of a Parisian jeweler, was born in Bruges, Belgium. A brilliant student, he entered the École polytechnique in 1833, where he befriended a teaching assistant who would later become famous: Joseph Liouville.
Great names for great numbers
Many mathematicians have lent their names to numbers in common use. "Very large" numbers have names too: a way had to be found to represent them as well, since they come up in several fields, from combinatorics to mathematical logic!
Carmichael numbers | Tangente
Does Fermat's little theorem characterize prime numbers? Far from it! Yet few composite numbers satisfy the theorem's conclusion, making them all the more intriguing to number-theory enthusiasts and specialists alike.
Fibonacci for rabbits | Tangente
These numbers are named after the 13th-century Italian mathematician Leonardo Fibonacci (c. 1175–c. 1250).
Perrin's test for primes… almost! | Tangente
The Perrin numbers are named after Raoul Perrin, a French engineer (1841–1910) who served as president of the Société mathématique de France in 1908.
Vauban… for the pigs | Tangente
Sébastien Le Prestre (1633–1707), Marquis de Vauban, better known simply as Vauban, was an eighteenth-century man of many talents: engineer, military architect, urban planner, encyclopedist… Louis XIV appointed him Marshal of France near the end of his life. He was responsible for numerous military fortresses throughout France.