Questions on more advanced topics of number theory. Consider first if (elementary-number-theory) might be a more appropriate tag before adding this tag.

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6
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About amicable numbers

My question might seem wrong but I will explain it now: We will define $\phi(a)$ as the sum of divisors of $a$ except $a$. A pair $(a,b)$ is an amicable pair $\iff ((\phi(a) = b) \land (\phi(b) = ...
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0answers
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Seeking proof for the formula relating Pi with its convergents

Could anyone try to prove that the below conjectured formula is valid for relating $\pi$ with ALL of its convergents - those, which are described in OEIS via A002485(n)/A002486(n) ? $$(-1)^n\cdot(\pi ...