Not to be confused with Ball bearing. Bearing balls are special highly spherical and smooth balls, most commonly used in ball bearings, but also used as components in things like freewheel mechanisms. The balls come in many different grades.
Euler Prime. Let a prime number generated by Euler's prime-generating polynomial be known as an Euler prime. Then the first few Euler primes occur for , 2, ..., 39, 42, 43, 45, ... (OEIS A056561), corresponding to the primes 43, 47, 53, 61, 71, 83, 97, 113, 131, 151, 173, ... (OEIS A005846).
Euler's Formula. Euler's identity is actually a special case of Euler's formula, e ^(i * x) = cos x + i sin x, when x is equal to pi. When x is equal to pi, cosine of pi equals -1 and sine of pi equals 0, and we get e ^(i *pi) = -1 + 0 i.