Gottfried Helms
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 47 Surprising identities / equations 43 Is there any simple method to calculate $\sqrt x$ without using logarithm 33 “The Egg:” Bizarre behavior of the roots of a family of polynomials. 33 Examples of apparent patterns that eventually fail 28 Mathematicians shocked(?) to find pattern in prime numbers

### Reputation (17,602)

 +20 How would I go about finding a closed form solution for $g(x,n) = f(f(f(…(x))))$, $n$ times? +35 Which primes $p$ divide $q^q-1$ for a prime divisor $q$ of $p-1$ +10 How to prove $(2^m-1)\nmid(2^n+1)$ if $m>2$ +10 Best fit ellipsoid

### Questions (119)

 21 How to prove $\lim_{n \to \infty} e^n \cdot \left( \sum_{k=0}^{n-1} ({k-n \over e})^k/k! \right)- 2 \cdot n = \frac 23$? 18 How can I prove my conjecture for the coefficients in $t(x)=\log(1+\exp(x))$? 17 Series of logarithms $\sum\limits_{k=1}^\infty \ln(k)$ (Ramanujan summation?) 14 Has someone seen a discussion of the (divergent) summation of $\sum\limits_{k=0}^\infty (-1)^k (k!)^2$? 14 I can Euler-sum $\sqrt{-\ln(1)}-\sqrt{-\ln(2)}+\sqrt{-\ln(3)}-\cdots$. But how can I do $\sqrt{-\ln(1)}+\sqrt{-\ln(2)}+\sqrt{-\ln(3))}+\cdots$?

### Tags (210)

 167 number-theory × 115 88 recreational-mathematics × 19 129 sequences-and-series × 135 87 collatz × 52 111 complex-analysis × 24 84 numerical-methods × 25 104 tetration × 43 81 real-analysis × 25 98 elementary-number-theory × 58 75 linear-algebra × 58

### Accounts (20)

 Mathematics 17,602 rep 22773 MathOverflow 2,532 rep 1820 Cross Validated 803 rep 713 Buddhism 567 rep 311 German Language 293 rep 29