Appell sequence
The sequence of polynomials
(1) |
with
is a geometric sequence and has trivially the properties
(2) |
and
(3) |
(see the binomial theorem). There are also other polynomial sequences (1) having these properties, for example the sequences of the Bernoulli polynomials, the Euler polynomials
and the Hermite polynomials
. Such sequences are called Appell sequences and their members are sometimes characterised as generalised monomials
, because of resemblance to the geometric sequence.
Given the first member , which must be a nonzero constant polynomial, of any Appell sequence (1), the other members are determined recursively by
(4) |
as one gives the values of the constants of integration ; thus the number sequence
determines the Appell sequence uniquely. So the choice yields a geometric sequence and the choice for the Bernoulli polynomials (http://planetmath.org/BernoulliPolynomialsAndNumbers).
The properties (2) and (3) areequivalent (http://planetmath.org/Equivalent3). The implication
may be shown byinduction
(http://planetmath.org/Induction) on . The reverseimplication is gotten by using the definition of derivative
:
See also http://en.wikipedia.org/wiki/Appell_polynomialsWiki.