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Rings and Modules Seminar
~ Abstracts ~

R. W. Quackenbush
qbush(at)cc(dot)umanitoba(dot)ca

Department of Mathematics
University of Manitoba

Thursday, March 19, 2009

Bernoulli Numbers, Umbral Calculus, and Universal Algebra
Abstract:

Define B0 := 1 and (B+1)n – Bn = 0 for n ≥ 2. That is,

B0 = 1, B1 = –1/2, B2 = 1/6, B3 = 0, B4 = 1/30, B5 = 0, ….
We refer to Bk as the kth Bernoulli number. Let us rewrite this definition into one equation:
e(B+1)x – eBx = x.
Hence,
x = e(B+1)x – eBx = eBxex – eBx1 = eBx(ex – 1),
and so,
eBx = x/(ex – 1).
But x/(ex – 1) + x/2 is an even function, and so B2n+1 = 0 for n ≥ 1.

This is the basic Umbral Calculus argument for the Bernoulli numbers; I will explain Umbral Calculus in terms of modern algebra.

pdf file


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