Unlike emeralds which could look as dark as black in lowlight, _____ hold on to their green and gold vibrancy even in candlelight giving them the nickname emeralds of the evening.
• phi, Φ
The relationship between a number in the Fibonacci sequence and the previous number more and more closely approaches the irrational number Φ, the longer the sequence is continued. And Φ describes nothing other than the golden section.
• prime number theorem
The prime number theorem says that PI of x is asymtotically equivalent to x over log x. As a reminder, two sequences a sub n and b sub n are asymtotically equivalent if the limit as n goes to infinity of a sub n over b sub n is one.
• psi, Ψ
An important part is also played by the golden angle which divides the angle of 360° in the proportions of the golden section. As an angle smaller than 180° proved to be more handy in practice the smaller of the resultant angles is called the golden angle