DirichletConvolve[f, g, n, m] gives the Dirichlet convolution of the expressions f and g.
Erfi
(Built-in Mathematica Symbol) Erfi[z] gives the imaginary error function erf(i z)/i.
GegenbauerC[n, m, x] gives the Gegenbauer polynomial C_n^(m)(x). GegenbauerC[n, x] gives the renormalized form lim_(m->0) C_n^(m)(x)/m.
RiemannSiegelTheta[t] gives the Riemann\[Dash]Siegel function \[CurlyTheta](t).
SiegelTheta[\[CapitalOmega], s] gives the Siegel theta function \[CapitalTheta] (\[CapitalOmega], s) with Riemann modular matrix \[CapitalOmega] and vector ...
SinhIntegral[z] gives the hyperbolic sine integral function Shi(z).
VonMisesDistribution[\[Mu], \[Kappa]] represents a von Mises distribution with mean \[Mu] and concentration \[Kappa].
NDSolve returns solutions as InterpolatingFunction objects. Most of the time, simply using these as functions does what is needed, but occasionally it is useful to access the ...
CosIntegral[z] gives the cosine integral function Ci(z).
RiemannSiegelZ[t] gives the Riemann\[Dash]Siegel function Z(t).