Gleason's polynomials are the sequence of monic integer polynomials defined recursively by $$ \prod_{d \mid n} G_d(c) = (((c^2+c)^2+c)^2+\cdots+c)^2+c \quad \quad \quad [\textrm{$n$ iterates}], $$ for $n=1,2, \ldots$. Thus they start out like: $$ G_1 = c, \quad G_2 = c+1, \quad G_3 = c^3 + 2c^2 ...

Background: If one works with sheaves on small etale site over a fixed scheme (which is really an essentially large category), one can instead work with sheaves on the affine etale site (which turns out to be an essentially small category) as their sheaves categories coincide. The consequence is ...