Prime Power Conjecture
An Abelian planar Difference Set of order 
exists only for a Prime Power. Gordon (1994) has verifiedit to be true for 
.
References
Gordon, D. M. ``The Prime Power Conjecture is True for .'' Electronic J. Combinatorics 1, R6 1-7, 1994.http://www.combinatorics.org/Volume_1/volume1.html#R6.
- Mechanical Quadrature
- Mecon
- Medial Axis
- Medial Deltoidal Hexecontahedron
- Medial Disdyakis Triacontahedron
- Medial Hexagonal Hexecontahedron
- Medial Icosacronic Hexecontahedron
- Medial Inverted Pentagonal Hexecontahedron
- Medial Pentagonal Hexecontahedron
- Medial Rhombic Triacontahedron
- Medial Triambic Icosahedron
- Medial Triangle
- Medial Triangle Locus Theorem
- Median Point
- Median (Statistics)
- Mediant
- Median (Triangle)
- Mega
- Megistron
- Mehler-Dirichlet Integral
- Mehler Quadrature
- Mehler's Bessel Function Formula
- Mehler's Hermite Polynomial Formula
- Meijer's G-Function
- Meissel's Formula