MathOverflow

Consider the Collatz function $T(n) = n/2$ if $n$ even, $T(n) = 3n+1$ if $n$ odd.
Restrict to $n \equiv 6 \pmod{8}$ and write $n = 8m + 6$. For odd $n$, let $C(n) = (3n+1)/2$.
Observation: For $n = 8m + 6$, the orbit under $T$ takes the form:$$8m + 6 \to 4m + 3 \to 12m + 10 = 2(6m + 5)$$...

Pillai's conjecture asserts that for each positive integer $k$, There are only finitely many pairs of numbers $(x^a,y^b)$ with $x,y,a,b$ positive integers $a,b$ greater than $1$, and $x^a-y^b=k$. Assuming it is true, let $S(k)$ be the number of such...

Let $\psi(x)$ denote the Chebyshev function and consider the classical explicit formula in the form
$$\psi(x) - x \sim \sum_{\rho} \frac{x^{\rho}}{\rho}= \sqrt{x} \sum_{\gamma} \frac{e^{i\gamma \log x}}{\tfrac{1}{2}+i\gamma},$$
where $\rho = \tfrac{1}{2} + i\gamma$ runs over the nontrivial zeros of $\zeta(s)$....

What tools do people use for quickly and easily creating presentable, if not publication quality, diagrams of various kinds?
When I need to make a high quality diagram, I'm happy to whip up some TikZ. TikZ is great for producing all kinds of publication quality diagrams with consistent typography and fine-grained control. However, in other contexts (e.g., a MO question/answer...