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Concrete mathematics : a foundation for computer science

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320 GENERATING FUNCTIONS<br />

Table 320 Generating function manipulations.<br />

G(~)-go-g,z-...-g,~,z~~’<br />

zm<br />

aF(z) + K(z) = t(h + Bsn)z”<br />

n<br />

s L<br />

0<br />

PG(z) = t<br />

n<br />

gn-mz ,<br />

;; gn+mz n ,<br />

n20<br />

G(a) = ~cngnzn<br />

n<br />

G’(z) = x(n+ l)gn+l P<br />

n<br />

zG’(z) = xngnz”<br />

n<br />

G(t) dt = x ;gn.-, 2”<br />

lI>l<br />

F(z)G(z) = t(tfxg,,)z”<br />

+;W = ;(;g+<br />

n kin<br />

integer m 3 0<br />

integer m 3 0<br />

Another useful special case arises when F(z) is the familiar function<br />

1/(1--z) = 1+z+z2+...; then all fk's (<strong>for</strong> k 3 0) are 1 and we have<br />

the important <strong>for</strong>mula<br />

&(z) = @

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