Number of terms. (1 Viewer)

Fus Ro Dah · Aug 20, 2012

I've been told that the notation might be hard to understand for those who haven't seen it before.

$(x_1)(x_1+x_2)(x_1+x_2+x_3)(x_1+x_2+x_3+x_4)...(x_1+x_2+x_3+x_4+x_5+...+x_n)$

seanieg89 · Aug 21, 2012

The n-th Catalan number:

$\frac{(2n)!}{n!(n+1)!}.$

seanieg89 · Aug 21, 2012

A little tired now, so will justify this tomorrow.

karnbmx · Aug 21, 2012

Fus Ro Dah said:
$$Find the number of terms in the expansion of $ \prod_{j=1}^{n}\left (\sum_{i=1}^{j} x_i \right )$

what does the weird pi like notation mean?

Carrotsticks · Aug 21, 2012

karnbmx said:
what does the weird pi like notation mean?

Product notation, just like the sigma for summing.

Except it's multiplying, so:

$\prod_{k=1}^{n}k^2 = 1^2 \times 2^2 \times 3^2 \times ... \times n^2$

Number of terms. (1 Viewer)

Fus Ro Dah

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seanieg89

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karnbmx

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Carrotsticks

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