The formula is (Current XP)+(previous level * 1000).
If lvl 10 = 45,000 exp and you want to know how much it is for lvl 11 -> 45,000 + 10*1000 = 55,000.

And the levels are:

LVL 10 45,000
lvl 11 55,000
lvl 12 66,000
lvl 13 78,000
lvl 14 91,000
lvl 15 105,000
lvl 16 120,000
lvl 17 136,000
lvl 18 153,000
lvl 19 171,000
lvl 20 190,000
lvl 21 210,000
lvl 22 231,000
lvl 23 253,000
lvl 24 276,000
lvl 25 300,000
lvl 26 325,000
lvl 27 351,000
lvl 28 378,000
lvl 29 406,000
lvl 30 436,000
lvl 31 466,000
lvl 32 497,000
lvl 33 529,000
lvl 34 562,000
lvl 35 596,000
lvl 36 631,000
lvl 37 667,000
lvl 38 704,000
lvl 39 742,000
lvl 40 781,000
lvl 41 821,000
lvl 42 862,000
lvl 43 904,000
lvl 44 947,000
lvl 45 991,000
lvl 46 1,036,000
lvl 47 1,082,000
lvl 48 1,129,000
lvl 49 1,117,000
lvl 50 1,226,000

Now you can go "ONLY 43208 EXP FOR NEXT LEVEL!

Enjoy :)

yes yes just drop 1000 of each level :P It's not a big difference anyway