- Sequence (Wikipedia)
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called elements, or terms). The number of elements (possibly infinite) is called the length of the sequence. Unlike a set, the same elements can appear multiple times at different positions in a sequence, and unlike a set, the order does matter. Formally, a sequence can be defined as a function from natural numbers (the positions of elements in the sequence) to the elements at each position. The notion of a sequence can be generalized to an indexed family, defined as a function from an arbitrary index set.
richard francis burton of
- Richard Francis Burton (Wikipedia)
Sir Richard Francis Burton KCMG FRGS (/ˈbɜːrtən/; 19 March 1821 – 20 October 1890) was a British explorer, writer, scholar, and soldier. He was famed for his travels and explorations in Asia, Africa, and the Americas, as well as his extraordinary knowledge of languages and cultures. According to one count, he spoke twenty-nine European, Asian, and African languages.