| Clue | Letter |
|---|
| coefficient of the real component of a complex number | |
| in number theory, the sum of the divisors of a positive integer | |
| twice the arcsine of 1, or the number of primes less than a given number | |
| the polygamma function, or the reciprocal Fibonacci constant | |
| an arbitrarily small positive quantity, used by Erdős to refer to children | |
| in graph theory, the smallest degree of any vertex in a graph | |
| commonly used to denote complex numbers, especially roots of unity | |
| representation of a group, or radius in spherical polar coordinates | |
| commonly used to denote a plane angle in Euclidean geometry | |
| number of positive integers less than and coprime to a given integer | |
| the Möbius function, which always takes on a value of -1, 0, or 1 | |
| | Clue | Letter |
|---|
| the limit of the ratios of successive terms in the Fibonacci sequence | |
| extension of the factorial function to complex numbers | |
| the function whose zeroes are the subject of the Reimann hypothesis | |
| a summation, has a subscript and sometimes a superscript | |
| the independent variable for the Fourier transform of a function | |
| change in a quantity, usually as it relates to change in another quantity | |
| character in representation theory, or chromatic number in graph theory | |
| Lagrange multipliers in calculus, or eigenvalues in linear algebra | |
| the least ordinal which the reals cannot map onto surjectively | |
| the connectivity of a graph, or the local connectivity of two vertices | |
| coefficient of the imaginary component of a complex number | |
| probably the most underused Greek letter, not sure why it isn't more common | |
| looks too much like a 1 to be used | |
| looks too much like a 0 to be used | |
| looks too much like a V to be used | |
| looks too much like a U to be used | |
| a bit too long to be used as a mathematical variable, methinks | |
|
The Nine Planets 
Digits of Pi 
Multiplication Table
