Triangular number
Revision as of 03:11, 8 September 2007 by I_like_pie (talk | contribs)
The triangular numbers are the numbers which are the sum of the first natural numbers from to .
Using the sum of an arithmetic series formula, a formula can be calculated for :
The rather simple recursive definition can be easily found by noting that .
This article is a stub. Help us out by expanding it.