出典:Wiktionary
binomial series (複数形 binomial series)
The infinite series is a direct generalisation of the (finite) binomial theorem expansion of (1 + x)n (n a positive integer): in both cases, the notation , as defined above, is applicable for the coefficients, which are called binomial coefficients. (Note that the binomial theorem treats the slightly different form (x + y)n, which does not directly generalise to an infinite series.)