Number theory................surprising connections between numbers................one of the books.....put it........"the curious repetition of 1828"...............

e (Euler's Number)

The number e is a famous irrational number, and is one of the most important numbers in mathematics.
The first few digits are:

2.7182818284590452353602874713527 (and more ...)

It is often called Euler's number after Leonhard Euler.
And Euler is spoken like "Oiler".