Integer sequences

class of natural numbers

odd number which would have been a perfect number if one of its composite factors were prime

the Cartesian product of countably infinitely many copies of the set of natural numbers with the product topology

number of partitions of an integer, often used in number theory

infinite sequence of symbols {1,2} that is its own run-length encoding and the prototype for an infinite family of related sequences

combinatorial sequence of numbers

generalization of total orderings allowing ties, axiomatized as strict weak orders, total preorders, or ordered partitions

mathematical sequence

numeral ambigram

unique real number solution to the equation x^3-x^2-1=0

number in a given base that has the same number of digits as the number of digits in its prime factorization in the given base

sequence equivalent to its runs transform

In number theory, a noncototient is a positive integer that cannot be expressed as the difference between a positive integer and the number of coprime integers below it. That is, , where stands for Euler's totient function, has no solution for . The cototient of is defined as , so a noncototient is a number that is never a cototient.

number of the form (2^n)−1

Result of multiplying seven instances of a number

In mathematics, an interprime is the average of two consecutive odd primes. For example, 9 is an interprime because it is the average of 7 and 11. The first interprimes are: 4, 6, 9, 12, 15, 18, 21, 26, 30, 34, 39, 42, 45, 50, 56, 60, 64, 69, 72, 76, 81, 86, 93, 99, ... Interprimes cannot be prime themselves (otherwise the primes would not have been consecutive).

sequence of natural numbers for which every positive integer can be expressed as a sum of values in the sequence, using each value at most once

number that is the sum of its iterated totients

mathematical concept

self-avoiding closed curve which intersects a line a number of times

a series of integer sequences proposed and named after Douglas Hofstadter

sequence of numbers counting certain kinds of binary trees

two theoretical number functions

sequence of coefficients

In math, a number that is equal to the sum of some of its factors

number in combinatorics

type of Poulet number

Integer sequence

sequence satisfying a homogeneous linear recurrence with constant coefficients

mathematics concept

infinite sequence of prime numbers

journal

result of multiplying eight instances of a number together

type of number

how many times a number is divisible by 2

sequence hypothesized to always terminate at 1

positive integer with large prime factors

assignment problem in combinatorial mathematics

class of positive integers