number.house
A catalogue of numbers and their mathematical, cultural, and linguistic properties.
50827792 numbers · 392,541 sequences · 69 properties
Featured sequences
- Number of groups of order n.A000001
- Kolakoski sequence: a(n) is length of n-th run; a(1) = 1; sequence consists just of 1's and 2's.A000002
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.A000003
- The zero sequence.A000004
- d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.A000005
- Integer part of square root of n-th prime.A000006
- The characteristic function of {0}: a(n) = 0^n.A000007
- Number of ways of making change for n cents using coins of 1, 2, 5, 10 cents.A000008