CatalanNumber[n] gives the n\[Null]^th Catalan number C_n.
ExactNumberQ[expr] returns True if expr is an exact real or complex number, and returns False otherwise.
ExponentFunction is an option for NumberForm and related functions that determines the exponent to use in printing approximate real numbers.
InverseJacobiCD[v, m] gives the inverse Jacobi elliptic function cd -1 (v \[VerticalSeparator] m).
InverseJacobiCN[v, m] gives the inverse Jacobi elliptic function cn -1 (v \[VerticalSeparator] m).
InverseJacobiCS[v, m] gives the inverse Jacobi elliptic function cs -1 (v \[VerticalSeparator] m).
InverseJacobiDC[v, m] gives the inverse Jacobi elliptic function dc -1 (v \[VerticalSeparator] m).
InverseJacobiDN[v, m] gives the inverse Jacobi elliptic function dn -1 (v \[VerticalSeparator] m).
InverseJacobiDS[v, m] gives the inverse Jacobi elliptic function ds -1 (v \[VerticalSeparator] m).
InverseJacobiNC[v, m] gives the inverse Jacobi elliptic function nc -1 (v \[VerticalSeparator] m).