219 (two hundred [and] nineteen) is the natural number following 218 and preceding 220.
In mathematics
- 219 is a happy number.[1]
- Mertens function (219) = 4, a record high.[2]
- There are 219 partially ordered sets on four labeled elements.[3]
- 219 is the smallest number that can be represented as a sum of four positive cubes in two different ways.[4]
- There are 219 different space groups, discrete and full-dimensional sets of symmetries of three-dimensional space or of crystal structures.
References
- ^ Sloane, N. J. A. (ed.). "Sequence A007770 (Happy numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A051400 (Smallest value of x such that M(x)=n, where M() is Mertens's function)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A001035 (Number of partially ordered sets ("posets") with n labeled elements (or labeled acyclic transitive digraphs))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A025420 (Least sum of 4 positive cubes in exactly n ways)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation..