You can put this solution on YOUR website! 144-121=23
121-100=21
100-81 =19
81-64 =17
Each step is lowering the value subtracted by 2, so we take 17 and subtract 2.
17-2=15
We then subtract 15 from 64.
64-15=49
49 is the next number in the sequence
Hope this helps. Good luck!