Some strange mathematical sequences are always whole numbers — until they’re not. The puzzling patterns have revealed ties to graph theory and prime numbers, awing mathematicians. Simple, yes, but ...

Recursion -- the computational capacity to embed elements within elements of the same kind -- has been lauded as the intellectual cornerstone of language, tool use and mathematics. A ...

Random digits are collected one at a time until a given k-digit sequence is obtained, or, more generally, until one of several k-digit sequences is obtained. In the former case, a recursive formula is ...