supersearches: [logic]
sidesearches: physics, philosophy
subsearches: [arithmetic], [elementary (high school/college) algebra], [calculus],
         linear algebra, [real analysis], [abstract algebra],


❦ Math

General resources
Wikipedia, Citizendium, NWE
AoPS wiki, Math wiki, nLab, HyperMath, PlanetMath
MIT Open Courseware
Khan Academy, Knowino

Proof Wiki
Brilliant.org articles
Tricki

Math Stack Exchange

Few-subject resources
3Blue1Brown
Math Proofs Jrensen

Eqworld
Human knowledge

Calculators and graphing
Desmos 2d graphing
Desmos 3d graphing

Other tools
OEIS
All LaTeX symbols list
Math genealogy

Floating point math
0.30000000000000004.com

Prime numbers
Prime wiki
Prime factorization visualization
GIMPS
The Prime Pages

Pending
Euler Map Theorem (V-E+F=2) Visual Proof
Wrath of Math: is everybody teaching this math wrong?
Trachtenberg system of multiplication Math map (quanta magazine)
https://www.malinc.se/