Mathematics/Number Theory

Digit Expansions
by Jonas Bayer, Marco David, Abhik Pal and Benedikt Stock

Irrational numbers from THE BOOK
by Lawrence C. Paulson

Lifting the Exponent
by Jakub Kądziołka

Hensel's Lemma for the p-adic Integers
by Aaron Crighton

The Hermite–Lindemann–Weierstraß Transcendence Theorem
by Manuel Eberl

Amicable Numbers
by Angeliki Koutsoukou-Argyraki

Irrationality Criteria for Series by Erdős and Straus
by Angeliki Koutsoukou-Argyraki and Wenda Li

Gaussian Integers
by Manuel Eberl

Lucas's Theorem
by Chelsea Edmonds

Furstenberg's topology and his proof of the infinitude of primes
by Manuel Eberl

Arithmetic progressions and relative primes
by José Manuel Rodríguez Caballero

Mersenne primes and the Lucas–Lehmer test
by Manuel Eberl

The Irrationality of ζ(3)
by Manuel Eberl

Gauss Sums and the Pólya–Vinogradov Inequality
by Rodrigo Raya and Manuel Eberl

The Transcendence of Certain Infinite Series
by Angeliki Koutsoukou-Argyraki and Wenda Li

Elementary Facts About the Distribution of Primes
by Manuel Eberl

Probabilistic Primality Testing
by Daniel Stüwe and Manuel Eberl

The Transcendence of π
by Manuel Eberl

The Prime Number Theorem
by Manuel Eberl and Lawrence C. Paulson

Pell's Equation
by Manuel Eberl

Irrational Rapidly Convergent Series
by Angeliki Koutsoukou-Argyraki and Wenda Li

Dirichlet L-Functions and Dirichlet's Theorem
by Manuel Eberl

Homogeneous Linear Diophantine Equations
by Florian Messner, Julian Parsert, Jonas Schöpf and Christian Sternagel

The Hurwitz and Riemann ζ Functions
by Manuel Eberl

Dirichlet Series
by Manuel Eberl

Minkowski's Theorem
by Manuel Eberl

Bernoulli Numbers
by Lukas Bulwahn and Manuel Eberl

Bertrand's postulate
by Julian Biendarra and Manuel Eberl

The Transcendence of e
by Manuel Eberl

The Divergence of the Prime Harmonic Series
by Manuel Eberl

Liouville numbers
by Manuel Eberl

The Stern-Brocot Tree
by Peter Gammie and Andreas Lochbihler

Pratt's Primality Certificates
by Simon Wimmer and Lars Noschinski

Lehmer's Theorem
by Simon Wimmer and Lars Noschinski

Perfect Number Theorem
by Mark Ijbema

Sums of Two and Four Squares
by Roelof Oosterhuis

Fermat's Last Theorem for Exponents 3 and 4 and the Parametrisation of Pythagorean Triples
by Roelof Oosterhuis