Fibonacci numbers

A number series of which the first two members are one; thereafter each member is the sum of the two preceding members. The series has interesting properties related to the golden section (familiar to students of proportion), and has connections with a variety of familiar natural phenomena, including: the number of emergent rays from multiple reflections of light; the number of different possible histories of an electron in the ideally simplified atoms of a quantity of hydrogen gas; the genealogical table of a bee; phyllotaxis, namely the arrangement of leaves on the stems of plants; and the equiangular spiral frequently encountered in petal arrangements in flowers, in shells, and in musical scale.