The sum of divisors of $n$
denote the sum of the divisors of .
G. Robin [
MR 86f:11069] showed that the Riemann Hypothesis is
for all , where is Euler's constant.
That inequality does not leave much to spare, for Gronwall showed
and Robin showed unconditionally that
J. Lagarias [
arXiv:math.NT/0008177] elaborated on Robin's
work and showed that the Riemann Hypothesis is equivalent to
for all , where is the harmonic number
so Lagarias' and Robin's inequalities are the same to leading order.
Back to the
for The Riemann Hypothesis.