*Édouard Lucas → French, German, Portuguese, Spanish.*

**François Édouard Anatole Lucas** (April 4, 1842 in Amiens - October 3, 1891) was a French mathematician. Lucas is known for his study of the Fibonacci sequence. The related Lucas sequence is named after him. He gave a formula for finding the n^{th} term of the Fibonacci sequence.

Lucas was educated at the École Normale Supérieure. He worked in the Paris observatory and later became a professor of mathematics in Paris. In the meantime he served in the army.

Lucas posed a challenge to prove that the only solution of the Diophantine equation:

with *N* > 1 is when *N*=24 and *M*=70. It was not until 1918 that a proof (using hyperelliptic functions) was found for this remarkable fact, which has relevance to the bosonic string theory in 26-dimensions [1].

He devised methods for testing the primality of numbers. In 1857, at age 15, Lucas began testing the primality of 2^{127}-1 by hand, using Lucas Sequences. In 1876, after 19 years of testing [2], he finally proved that 2^{127}−1 was prime; this would remain the largest known Mersenne prime for three-quarters of a century. This may stand forever as the largest prime number proven by hand. Later Derrick Henry Lehmer refined Lucas' primality tests and obtained the Lucas-Lehmer test for Mersenne numbers.

He worked on the development of the umbral calculus.

Lucas was also interested in recreational mathematics. He discovered an elegant binary solution to the Baguenaudier puzzle. He also more notably invented the Tower of Hanoi puzzle in 1883, which he marketed under the nickname *N. Claus de Siam*, an anagram of *Lucas d'Amiens*. He also invented Dots-and-Boxes in 1889 (he called the game *La Pipopipette*) and probably Tchuka Ruma.

Lucas died in unusual circumstances. At the banquet of the annual congress of the *Association française pour l'avancement des sciences* a waiter dropped some crockery and a piece of broken plate cut Lucas on the cheek. He died a few days later of a severe skin inflammation probably caused by septicemia. Lucas was only 49 years old when he died.

## External Links

- O'Connor, John J. & Robertson, Edmund F., “Édouard Lucas”, MacTutor History of Mathematics archive
- Scans of Lucas's original Tower of Hanoi puzzle in French, with translations
- Édouard Lucas, by Clark Kimberling
- Édouard Lucas, the official web-site.

## Copyright

Adapted from the Wikipedia article, "Édouard Lucas" http://en.wikipedia.org/wiki/%C3%89douard_Lucas, used under the GNU Free Documentation License.