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).
n!! gives the double factorial of n.
GCD
(Built-in Mathematica Symbol) GCD[n_1, n_2, ...] gives the greatest common divisor of the n_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.
GroupStabilizerChain[group] returns a list of successive stabilizers in group of the points in a base of group.
Hypergeometric1F1[a, b, z] is the Kummer confluent hypergeometric function \[Null]_1 F_1 (a; b; z).
HypergeometricU[a, b, z] is the confluent hypergeometric function U(a, b, z).
LaguerreL[n, x] gives the Laguerre polynomial L_n (x). LaguerreL[n, a, x] gives the generalized Laguerre polynomial L_n^a(x).
LCM
(Built-in Mathematica Symbol) LCM[n_1, n_2, ...] gives the least common multiple of the n_i.