Can Frobenius Method start with the ∑ starting from 1?

Question

So, the terms I obtained was 0 for the whole series as the 1st term I obtained was also 0. However, when the question was done with ∑ starting with 0, it gives a nice series of answer. So, does that mean that solving Frobenius method should start with the ∑ of 1 and not any other integer? The Differential Equation for the question is : xy"+(1+x)y'+ny=0