DivisorSigma (Built-in Mathematica Symbol)

DivisorSigma[k, n] gives the divisor function \[Sigma]_k (n).

Erfi (Built-in Mathematica Symbol)

Erfi[z] gives the imaginary error function erf(i z)/i.

EulerE (Built-in Mathematica Symbol)

EulerE[n] gives the Euler number E_n. EulerE[n, x] gives the Euler polynomial E_n (x).

GCD (Built-in Mathematica Symbol)

GCD[n_1, n_2, ...] gives the greatest common divisor of the n_i.

GegenbauerC (Built-in Mathematica Symbol)

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.

HypergeometricU (Built-in Mathematica Symbol)

HypergeometricU[a, b, z] is the confluent hypergeometric function U(a, b, z).

LCM (Built-in Mathematica Symbol)

LCM[n_1, n_2, ...] gives the least common multiple of the n_i.

NorlundB (Built-in Mathematica Symbol)

NorlundB[n, a] gives Nørlund polynomials B_n^(a) of degree n in a.NorlundB[n, a, x] gives generalized Bernoulli polynomials B_n^(a)(x).

Quotient (Built-in Mathematica Symbol)

Quotient[m, n] gives the integer quotient of m and n. Quotient[m, n, d] uses an offset d.

RamanujanTau (Built-in Mathematica Symbol)

RamanujanTau[n] gives the Ramanujan \[Tau] function \[Tau](n).