Paper 4, Section I, G

Number Theory
Part II, 2017

Show that, for x2x \geqslant 2 a real number,

pxp is prime (11p)1>logx\prod_{\substack{p \leqslant x \\ p \text { is prime }}}\left(1-\frac{1}{p}\right)^{-1}>\log x

Hence prove that

px,p is prime 1p>loglogx+c,\sum_{\substack{p \leqslant x, p \text { is prime }}} \frac{1}{p}>\log \log x+c,

where cc is a constant you should make explicit.