The reason is simple. The time in your code start from 1 where as online calculators start from 0.
If you adjusted your equation to account for the start time (t+1 term), then you need to input t = 24 in the online calculator solution.
The online calculator solution is;
If you put t = 24, which means 25 seconds in reality due to +1 adjustment (online calculator answers t range is 0 to 24, with the +1 adjustment you make it 1 to 25), you will get;
x = 1.1*(t+1)^(1/10)
x = 1.1*(24+1)^(1/10)
x = 1.5177
which is what your Euler method finds.