A list of articles with mathematical proofs:
Theorems of which articles are primarily devoted to proving them
Bertrand's postulate and a proof
Estimation of covariance matrices
Fermat's little theorem and some proofs
Gödel's completeness theorem and its original proof
Mathematical induction and a proof
Proof that 0.999... equals 1
Proof that 22/7 exceeds π
Proof that e is irrational
Proof that π is irrational
Proof that the sum of the reciprocals of the primes diverges
Articles devoted to theorems of which a (sketch of a) proof is given
Banach fixed-point theorem
Banach–Tarski paradox
Basel problem
Bolzano–Weierstrass theorem
Brouwer fixed-point theorem
Buckingham π theorem (proof in progress) Burnside's lemma Cantor's theorem Cantor–Bernstein–Schroeder theorem Cayley's formula Cayley's theorem Clique problem (to do) Compactness theorem (very compact proof) Erdős–Ko–Rado theorem Euler's formula Euler's four-square identity Euler's theorem Five color theorem Five lemma Fundamental theorem of arithmetic Gauss–Markov theorem (brief pointer to proof) Gödel's incompleteness theorem Gödel's first incompleteness theorem Gödel's second incompleteness theorem Goodstein's theorem Green's theorem (to do) Green's theorem when D is a simple region Heine–Borel theorem Intermediate value theorem Itô's lemma Kőnig's lemma Kőnig's theorem (set theory) Kőnig's theorem (graph theory) Lagrange's theorem (group theory) Lagrange's theorem (number theory) Liouville's theorem (complex analysis) Markov's inequality (proof of a generalization) Mean value theorem Multivariate normal distribution (to do) Holomorphic functions are analytic Pythagorean theorem Quadratic equation Quotient rule Ramsey's theorem Rao–Blackwell theorem Rice's theorem Rolle's theorem Splitting lemma squeeze theorem Sum rule in differentiation Sum rule in integration Sylow theorems Transcendence of e and π (as corollaries of Lindemann–Weierstrass) Tychonoff's theorem (to do) Ultrafilter lemma Ultraparallel theorem Urysohn's lemma Van der Waerden's theorem Wilson's theorem Zorn's lemma
Articles devoted to algorithms in which their correctness is proved
Bellman–Ford algorithm (to do) Euclidean algorithm Kruskal's algorithm Gale–Shapley algorithm Prim's algorithm Shor's algorithm (incomplete)
Articles where example statements are proved
Basis (linear algebra) Burrows–Abadi–Needham logic Direct proof Generating a vector space Linear independence Polynomial Proof Pumping lemma Simpson's rule
Other articles containing proofs
Accumulation point
Addition in N
associativity of addition in N
commutativity of addition in N
uniqueness of addition in N
Algorithmic information theory
Boolean ring
commutativity of a boolean ring
Boolean satisfiability problem
NP-completeness of the Boolean satisfiability problem
Cantor's diagonal argument
set is smaller than its power set
uncountability of the real numbers
Cantor's first uncountability proof
uncountability of the real numbers
Combinatorics
Combinatory logic
Co-NP
Coset
Countable
countability of a subset of a countable set (to do) Angle of parallelism Galois group Fundamental theorem of Galois theory (to do) Gödel number Gödel's incompleteness theorem Group (mathematics) Halting problem insolubility of the halting problem Harmonic series (mathematics) divergence of the (standard) harmonic series Highly composite number Area of hyperbolic sector, basis of hyperbolic angle Infinite series convergence of the geometric series with first term 1 and ratio 1/2 Integer partition Irrational number irrationality of log23 irrationality of the square root of 2 Mathematical induction sum identity Power rule differential of xn Product and Quotient Rules Derivation of Product and Quotient rules for differentiating. Prime number Infinitude of the prime numbers Primitive recursive function Principle of bivalence no propositions are neither true nor false in intuitionistic logic Recursion Relational algebra (to do) Solvable group Square root of 2 Tetris Algebra of sets idempotent laws for set union and intersection