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Feb
7
accepted Complex derivative numerically using real $h$ and imaginary $h i$?
Jan
6
accepted Stuck with LDU-factorization of a matrix where D should contain zeros
Jan
3
accepted Fermat-quotient of “order” 3: I found $68^{112} \equiv 1 \pmod {113^3}$ - are there bigger examples known?
Nov
4
accepted How to find cases where $m^2$ is near to $2^A$?
Oct
20
accepted Given a natural number $a$ find its index in a set of structural descriptions
Sep
5
accepted Series seems to converge extremely slow, but possibly towards 1. Does it possibly have a closed form?
May
8
accepted Is the sum of the reciprocals of the squarefree numbers divergent or convergent?
Mar
13
accepted Has someone seen a discussion of the (divergent) summation of $\sum\limits_{k=0}^\infty (-1)^k (k!)^2 $?
Sep
21
accepted Interpolated Fibonacci numbers - real or complex?
Sep
4
accepted How is the formal inverse of a power series with constant term developed ( for instance $\cosh^{-1}(x)$)?
Aug
20
accepted Does the inverse of this matrix of size $n \times n$ approach the zero-matrix in the limit as $\small n \to \infty$?
Aug
10
accepted Limit of differences of truncated series and integrals give Euler-gamma, zeta and logs. Why?
Aug
5
accepted What is the family of generating functions for the *rows* of this Stirling-number matrix for whose columns they are $\exp(\exp(x)-1)-1 $?
Jul
13
accepted What is the range of convergence of $\sum_{k=0}^\infty (k \cdot x \exp(-x))^k\cdot {1 \over k!} \cdot {1\over k+1}$?
Jul
4
accepted A better approximation of $({n \over e})^n$ than by $ \Gamma(1+n-1/2)$ ? (Focus is “reverse” to the Stirling approximation)
Jul
4
accepted LambertW: $ x=W(x\cdot e^{x}) $ for $ x \ge -1$ but not for $x \lt-1$. How do I express my formula/my text?
Apr
25
accepted We know $ \lim_{b \to 1}f_b(n)=n$ when $f_b(n)={b^n -1\over b-1}$ . How can we derive the limit for the inverse of $f_b(x)$?
Jan
24
accepted What is the *correct* (matrix) square-root of $A_2=\begin{bmatrix} 0&-1 \\ 1& 2 \end{bmatrix} $?
Nov
4
accepted $m \in \{2,6,42,1806,…\} $ - a problem of sum-of-$m$'th powers modulo $m$
Oct
30
accepted I've seen “hyperbolic rotation” - from this: generalization to multisection rotation: is this possible?