addition chain
An addition chain is a sequence
of integers of length such that each term for (with ) is the sum of two previous terms in at least one way. In the sum it is not required that . For example, 1, 2, 3, 5, 10, 20, 40, 80, is an addition chain of length 7: 3 is 1 + 2, 5 = 2 + 3, 10 = 5 + 5, and the rest have .
There are various subclassifications of addition chains, such as the Lucas chains. A Mian-Chowla sequence
is an addition chain with the restriction
that each term is the sum of two previous terms in only one way. The length may be infinite
, and thus the Fibonacci sequence
is an addition chain.