LiouvilleLambda[n] gives the Liouville function \[Lambda](n).
Log10
(Built-in Mathematica Symbol) Log10[x] gives the base-10 logarithm of x.
MangoldtLambda[n] gives the von Mangoldt function \[CapitalLambda](n).
MathieuCharacteristicA[r, q] gives the characteristic value a_r for even Mathieu functions with characteristic exponent r and parameter q.
MathieuCharacteristicB[r, q] gives the characteristic value b_r for odd Mathieu functions with characteristic exponent r and parameter q.
MathieuCharacteristicExponent[a, q] gives the characteristic exponent r for Mathieu functions with characteristic value a and parameter q.
MathieuCPrime[a, q, z] gives the derivative with respect to z of the even Mathieu function with characteristic value a and parameter q.
MathieuSPrime[a, q, z] gives the derivative with respect to z of the odd Mathieu function with characteristic value a and parameter q.
OverscriptBox[x, y] is the low-level box representation for OverscriptBox[x, y] in notebook expressions.
PrimeNu
(Built-in Mathematica Symbol) PrimeNu[n] gives the number of distinct primes \[Nu](n) in n.