RosettaCodeData/Task/Pascals-triangle/00DESCRIPTION

[[wp:Pascal's triangle|Pascal's triangle]] is an arithmetic and geometric figure often associated with the name of [[wp:Blaise Pascal|Blaise Pascal]], but also studied centuries earlier in India, Persia, China and elsewhere.

Its first few rows look like this:
     1
    1 1
   1 2 1
  1 3 3 1
where each element of each row is either 1 or the sum of the two elements right above it.

For example, the next row of the triangle would be:
:::   '''1'''   (since the first element of each row doesn't have two elements above it)
:::   '''4'''   (1 + 3)
:::   '''6'''   (3 + 3)
:::   '''4'''   (3 + 1)
:::   '''1'''   (since the last element of each row doesn't have two elements above it)

So the triangle now looks like this:
     1
    1 1
   1 2 1
  1 3 3 1
 1 4 6 4 1

Each row &nbsp; <tt> n </tt> &nbsp; (starting with row &nbsp; 0 &nbsp; at the top) shows the coefficients of the binomial expansion of &nbsp; <big><big> (x + y)<sup>n</sup>. </big></big>


;Task:
Write a function that prints out the first &nbsp; <tt> n </tt> &nbsp; rows of the triangle &nbsp; (with &nbsp; <tt> f(1) </tt> &nbsp; yielding the row consisting of only the element '''1''').

This can be done either by summing elements from the previous rows or using a binary coefficient or combination function.

Behavior for &nbsp; <big><tt> n ≤ 0 </tt></big> &nbsp; does not need to be uniform, but should be noted.


;See also:
* [[Evaluate binomial coefficients]]
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