There are several related series that are known as the binomial series.
The most general is
(1)
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where is a binomial coefficient and is a real number. This series converges for an integer, or (Graham et al. 1994, p. 162). When is a positive integer , the series terminates at and can be written in the form
(2)
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The theorem that any one of these (or several other related forms) holds is known as the binomial theorem.
Special cases give the Taylor series
(3)
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(4)
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where is a Pochhammer symbol and . Similarly,
(5)
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(6)
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which is the so-called negative binomial series.
In particular, the case gives
(7)
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(8)
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(9)
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(OEIS A001790 and A046161), where is a double factorial and is a binomial coefficient.
The binomial series has the continued fraction representation
(10)
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(Wall 1948, p. 343).