TITLE: Predict next number from a series
QUESTION [9 upvotes]: Which methods I can use to predict next number from a series of numbers ?
I know the min & max possible number in advance.

REPLY [2 votes]: Since release 1.0 of the Sympy module, you can also use the sympy.concrete.guess submodule (written by myself for the project); have a glance at the docstring documentation at https://raw.githubusercontent.com/sympy/sympy/master/sympy/concrete/guess.py where you will find various examples.
For instance:
>>> from sympy.concrete.guess import guess_generating_function as ggf
>>> ggf([k+1 for k in range(12)], types=['ogf', 'lgf', 'hlgf'])
{'hlgf': 1/(-x + 1), 'lgf': 1/(x + 1), 'ogf': 1/(x**2 - 2*x + 1)}

>>> from sympy import sympify
>>> l = sympify("[3/2, 11/2, 0, -121/2, -363/2, 121]")
>>> ggf(l)
{'ogf': (x + 3/2)/(11*x**2 - 3*x + 1)}

>>> from sympy import fibonacci
>>> ggf([fibonacci(k) for k in range(5, 15)], types=['ogf'])
{'ogf': (3*x + 5)/(-x**2 - x + 1)}

>>> from sympy import simplify, factorial
>>> ggf([factorial(k) for k in range(12)], types=['ogf', 'egf', 'lgf'])
{'egf': 1/(-x + 1)}

>>> ggf([k+1 for k in range(12)], types=['egf'])
{'egf': (x + 1)*exp(x), 'lgdegf': (x + 2)/(x + 1)}

N-th root of a rational function can also be detected (below is an example
coming from the sequence A108626 from http://oeis.org).
The greatest n-th root to be tested is specified as maxsqrtn (default 2).

>>> ggf([1, 2, 5, 14, 41, 124, 383, 1200, 3799, 12122, 38919])['ogf']
sqrt(1/(x**4 + 2*x**2 - 4*x + 1))

Note however that the module is rather oriented toward the detection of generating functions (and not direct formulas).