All open problems
Source labels openChecked July 26, 2026

WikipediaNumber theory

Lander, Parkin, and Selfridge Conjecture: Five Three

Special case of the Lander–Parkin–Selfridge conjecture: there is no solution in positive integers to x15+x25+x35=y5.x_1^5 + x_2^5 + x_3^5 = y^5. That is, for all x1,x2,x3,yNx_1, x_2, x_3, y \in \mathbb{N} with x1,x2,x3,y>0x_1, x_2, x_3, y > 0, x15+x25+x35y5.x_1^5 + x_2^5 + x_3^5 \neq y^5. This co...

Mathematical statement

Special case of the Lander–Parkin–Selfridge conjecture: there is no solution in positive integers to x15+x25+x35=y5.x_1^5 + x_2^5 + x_3^5 = y^5. That is, for all x1,x2,x3,yNx_1, x_2, x_3, y \in \mathbb{N} with x1,x2,x3,y>0x_1, x_2, x_3, y > 0, x15+x25+x35y5.x_1^5 + x_2^5 + x_3^5 \neq y^5. This corresponds to the case k=5k = 5, n=3n = 3, m=1m = 1 of the general conjecture, where n+m=4<5=kn + m = 4 < 5 = k would be required to yield a counterexample.

Statement source: Wikipedia statement material

Statement terms: Source-specific

Source-specific terms. Therefore does not assert reuse rights beyond attributed display.

Statement artifacts, not proofs

These records expose exact Lean propositions and statement-only wrappers. Defining a proposition does not supply a proof of it. A placeholder-bearing target also contains no proof. Elaboration checks syntax and types; it does not certify that a formalization perfectly captures every nuance of the informal problem.

Pinned Lean formulation 1

lander_parkin_selfridge.variants.five_three

Canonical source
Complete statement target, proof intentionally absentLean 4
theorem lander_parkin_selfridge.variants.five_three :     x₁ x₂ x₃ y : ,      0 < x₁  0 < x₂  0 < x₃  0 < y       x₁ ^ 5 + x₂ ^ 5 + x₃ ^ 5  y ^ 5 := by  sorry
Statement source
Formal Conjectures
Lean version
v4.27.0
Placeholder
Present; no proof artifact
Source evidence
Pinned source index
Fidelity review
Community formulation

References