Consider a discrete set of objects and a sample of size
N
taken with replacement from the set, producing a list of counts of the
objects that corresponds to a partition of
N . Two statistics
that are commonly used for measuring the "diversity" of the sample
are the Gini-Simpson index and the Shannon index. We study the number
of possible values that these indices can take across all possible
partitions of the sample size
N as
N increases. The two
statistics are highly correlated over the set of partitions of
N.
However, the number of possible values that the Shannon index
can take (
A383683) far
exceeds the number of possible values of the Gini-Simpson index (
A069999), with the latter growing
quadratically and the former growing faster than every polynomial.
Received May 20 2025; revised versions received May 21 2025; December 19 2025; February
10 2026.
Published in Journal of Integer Sequences,
February 10 2026.