  The Online Encyclopedia of Integer Sequences (OEIS) is made up of thousands
of numerical sequences considered particularly interesting by some
mathematicians. The graphic representation of the frequency with which a number
n as a function of n appears in that database shows that the underlying
function decreases fast, and that the points are distributed in a cloud,
seemingly split into two by a clear zone that will be referred to here as
"Sloane's Gap". The decrease and general form are explained by mathematics, but
an explanation of the gap requires further considerations.
