$\pi (t)-\operatorname {\textrm {li}}(t)$
$\boldsymbol {L}$-FUNCTIONS
$\boldsymbol {L}$-FUNCTIONS
$\boldsymbol{L(\sigma ,\chi )}$
$$\sum\limits_{l + km = n} {\sigma (l)\sigma (m)} $$ AND
$$\sum\limits_{al + bm = n} {\sigma (l)\sigma (m)} $$ FOR k = a · b = 21, 33, AND 35