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Concrete mathematics : a foundation for computer science

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Warning: This stuff<br />

is fairly advanced.<br />

Better skim the<br />

next two pages on<br />

first reading; they<br />

aren't crucial.<br />

-Friendly TA<br />

Start<br />

Skimming<br />

3.5 FLOOR/CEILING SUMS 87<br />

In the general case we can let a = Lfij; then we merely need to add<br />

the terms <strong>for</strong> a2 < k < n, which are all equal to a, so they sum to (n - a2)a.<br />

This gives the desired closed <strong>for</strong>m,<br />

x lJi;J = na-ia3-ia2-ia, a = [J;;J. (3.27)<br />

O

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