(mathematics) The number of ways to partition a set of n objects into k non-empty subsets, denoted by S(n,k).

(genetics) The number of chromosomes in each cell of an organism

(mathematics) For some number n, the maximum number of regions into which a cube can be partitioned by exactly n planes.

(mathematics) A number which results from the summation of consecutive triangular numbers, starting from 1. If the triangular numbers in such a summation are depicted as horizontal triangular arrays of units then these arrays can be stacked vertically to yield a tetrahedral array.

(mathematics) Synonym of Stirling number of the second kind

(spirituality) A number or sequence of numbers that a person frequently notices in the world around them, believed to be a message from benevolent angels.

(mathematics) A natural number whose square cannot be written as the sum of two nonzero squares.

Any member of an integer sequence that has the same recursive relationship as the Fibonacci sequence, i.e. each term is the sum of the two previous terms, but with different starting values such that the ratios of successive terms approach the golden ratio.

(combinatorics) Any member of a sequence of numbers that count the possible partitions of a set, such that the nth number Bₙ is the number of different ways to partition a set that has exactly n elements.

numberless; endless or infinite