UnitVector[k] gives the two-dimensional unit vector in the k\[Null]^th direction.UnitVector[n, k] gives the n-dimensional unit vector in the k\[Null]^th direction.
Permutations are basic elements in algebra. They have a natural non-commutative product (as matrices do as well), and hence can encode highly nontrivial structures in a ...
Fold
(Built-in Mathematica Symbol) Fold[f, x, list] gives the last element of FoldList[f, x, list].
AngerJ
(Built-in Mathematica Symbol) AngerJ[\[Nu], z] gives the Anger function J_v(z).AngerJ[\[Nu], \[Mu], z] gives the associated Anger function J_\[Nu]^\[Mu](z).
CatalanNumber[n] gives the n\[Null]^th Catalan number C_n.
ChartElements is an option to charting functions such as BarChart that specifies the graphics to use as the basis for bars or other chart elements.
DawsonF
(Built-in Mathematica Symbol) DawsonF[z] gives the Dawson integral F(z).
DirichletL[k, j, s] gives the Dirichlet L-function L(\[Chi], s) for the Dirichlet character \[Chi](n) with modulus k and index j.
FiniteAbelianGroupCount[n] gives the number of finite Abelian groups of order n.
HurwitzLerchPhi[z, s, a] gives the Hurwitz\[Dash]Lerch transcendent \[CapitalPhi](z, s, a).