The experience formula

I know I forget this every few months, so here it is thanks to kevinodie and Jassper who posted this on the official forums:

(Current Level * NextLevel)*500 = XP needed for next level.

So level 1 = 0xp,
(level 1 * Level 2)*500 = (1*2)=2*500= 1000 xp for level 2
(level 2 * Level 3)*500 = (2*3)=6*500= 3000 xp for level 3
ect.

This can also be expressed:

N*(N-1)*500 is the minimum XP needed to get to Nth level.