I did a rough calculation to show how many onions you can in each round. n is the number of onions you have before the 16th airdrop. If you have 1000 onions now, you'll get 69 onions roughly in each round from round 16-30.
In airdrop[16], you get you can n*0.069444 onions, and now you have n*(1+(25.0/360.0)) = n*1.069444 onions
In airdrop[17], you get n*0.069444 onions, and now you have n*1.069444*(1+(25.0/385.0)) = n*1.138889 onions
In airdrop[18], you get n*0.069444 onions, and now you have n*1.138889*(1+(25.0/410.0)) = n*1.208333 onions
In airdrop[19], you get n*0.069444 onions, and now you have n*1.208333*(1+(25.0/435.0)) = n*1.277778 onions
In airdrop[20], you get n*0.069444 onions, and now you have n*1.277778*(1+(25.0/460.0)) = n*1.347222 onions
In airdrop[21], you get n*0.069444 onions, and now you have n*1.347222*(1+(25.0/485.0)) = n*1.416667 onions
In airdrop[22], you get n*0.069444 onions, and now you have n*1.416667*(1+(25.0/510.0)) = n*1.486111 onions
In airdrop[23], you get n*0.069444 onions, and now you have n*1.486111*(1+(25.0/535.0)) = n*1.555556 onions
In airdrop[24], you get n*0.069444 onions, and now you have n*1.555556*(1+(25.0/560.0)) = n*1.625000 onions
In airdrop[25], you get n*0.069444 onions, and now you have n*1.625000*(1+(25.0/585.0)) = n*1.694444 onions
In airdrop[26], you get n*0.069444 onions, and now you have n*1.694444*(1+(25.0/610.0)) = n*1.763889 onions
In airdrop[27], you get n*0.069444 onions, and now you have n*1.763889*(1+(25.0/635.0)) = n*1.833333 onions
In airdrop[28], you get n*0.069444 onions, and now you have n*1.833333*(1+(25.0/660.0)) = n*1.902778 onions
In airdrop[29], you get n*0.069444 onions, and now you have n*1.902778*(1+(25.0/685.0)) = n*1.972222 onions
In airdrop[30], you get n*0.069444 onions, and now you have n*1.972222*(1+(25.0/710.0)) = n*2.041667 onions
In airdrop[31], you get n*0.083333 onions, and now you have n*2.041667*(1+(30.0/735.0)) = n*2.125000 onions
In airdrop[32], you get n*0.083333 onions, and now you have n*2.125000*(1+(30.0/765.0)) = n*2.208333 onions
In airdrop[33], you get n*0.083333 onions, and now you have n*2.208333*(1+(30.0/795.0)) = n*2.291667 onions
In airdrop[34], you get n*0.083333 onions, and now you have n*2.291667*(1+(30.0/825.0)) = n*2.375000 onions
In airdrop[35], you get n*0.083333 onions, and now you have n*2.375000*(1+(30.0/855.0)) = n*2.458333 onions
In airdrop[36], you get n*0.083333 onions, and now you have n*2.458333*(1+(30.0/885.0)) = n*2.541667 onions
In airdrop[37], you get n*0.083333 onions, and now you have n*2.541667*(1+(30.0/915.0)) = n*2.625000 onions
In airdrop[38], you get n*0.083333 onions, and now you have n*2.625000*(1+(30.0/945.0)) = n*2.708333 onions
In airdrop[39], you get n*0.083333 onions, and now you have n*2.708333*(1+(30.0/975.0)) = n*2.791667 onions
In airdrop[40], you get n*0.097222 onions, and now you have n*2.791667*(1+(35.0/1005.0)) = n*2.888889 onions
You can find the discussion in official forum
https://deeponion.org/community/threads/calculate-how-many-onions-you-can-have-after-each-airdrop.5381/