Mining

[Sum41Freeeeek]

(mining level + 1)*100*(mining level + 1)/2))

if your level was 0:
1*100*.5 = 50 rocks needed for level 1

if your level was 1:
2*100*1 = 200 rocks needed for level 2

if your level was 2:
3*100*1.5 = 450 rocks needed for level 3

Level 1: 50
Level 2: 200
Level 3: 450
Level 4: 800
Level 5: 1250
Level 6: 1800
Level 7: 2450
Level 8: 3200
Level 9: 4050
Level 10: 5000
Level 11: 6050
Level 12: 7200
Level 13: 8450
Level 14: 9800
Level 15: 11250
Level 16: 12800
Level 17: 14450
Level 18: 16200
Level 19: 18050
Level 20: 20000
Level 21: 22050
Level 22: 24200
Level 23: 26450
Level 24: 28800
Level 25: 31250
Level 26: 33800
Level 27: 36450
Level 28: 39200
Level 29: 42050
Level 30: 45000

I'm pretty sure that's correct. Don't take my word for it though.