Math::Sequence defines a class for simple mathematic sequences with a
recursive definition such as x_(n+1) = 1 / (x_n + 1). Creation of a
Math::Sequence object is described below in the paragraph about the
constructor.

Math::Sequence uses Math::Symbolic to parse and modify the recursive
sequence definitions. That means you specify the sequence as a string
which is parsed by Math::Symbolic. Alternatively, you can pass the
constructor a Math::Symbolic tree directly.

Because Math::Sequence uses Math::Symbolic for its implementation, all
results will be Math::Symbolic objects which may contain other variables
than the sequence variable itself.

Each Math::Sequence object is an iterator to iterate over the elements of
the sequence starting at the first element (which was specified by the
starting element, the second argument to the new() constructor). It offers
facilities to cache all calculated elements and access any element
directly, though unless the element has been cached in a previous
calculation, this is just a shortcut for repeated use of the iterator.

WWW: https://metacpan.org/release/Math-Sequence