Problem 5. Triangle Numbers

Okay, so we can definitely do better than a for loop...

@Micah Beckman no, this solution is not an "efficient" answer even though it scores high... one should use sum(1:n) to replace a for loop sum.

While people are tricking the scoring mechanism using regexp, sum(1:n) isn't the most efficient.

It's helpful to recognize that this is an arithmetic series starting at 1 and ending at n with an increments of 1. The sum of such an arithmetic series is n*(n+1)/2. You can see the difference if you use 'tic' 'toc' to time sum(1:n) and n*(n+1)/2 for very large n.