I just got to 29. It took around 32,500 XP.
To get to 30, it takes 67,359 XP.
I will imagine the same thing happens at 39, where the required XP doubles to some obscene amount like 200,000, and again at 49 to 400,000+.
According to clare, it took 366,464 XP to level up to 99.
If this pattern continues, I will be wrong when I said reaching 60 will be equivalent to reaching 80 pre-reset. Reaching 60 will be equivalent to reaching well beyond 100, perhaps even above 110 or 120. It will take at least as much XP to reach 60 as it would to reach 100 in the Beta, and that's with a cap on daily XP donations of a few thousand, along with a nerf to exploitable mechanics that made fast leveling so easy before, like ice crunching/sno cones/gurly drinks + butterflies/pork fountains.
EDIT: after reaching 30 and requiring 44k to level up to 31 I've realized I'm wrong about this. The doubling only affects the level before each increment of 10; after that, the total XP required is increased by 10k of what it was prior to the doubling. 39-->40, by this estimate, should take around 100k XP with 40-->41 taking 60k.