Question: for loop must be numeric or character troubles with exp(x)

Hi,

I'm trying to use powsolve to give me the power series of a differential equation. It's been working wonderfully, afaik, but once I put in exp(x) it refuses to run. Here's my code:

 >with(powseries);

>a := powsolve(diff(y(x), x, x)+y*exp(x) = 0, y(0) = 1, (D(y))(0) = 2); tpsform(a, x)

 

and the error I'm getting:

Error, (in powseries:-powsolve) final value in for loop must be numeric or character
 
as I said, I had run it earlier with code like this:
>a := powsolve(diff(y(x), x)+y(x)*x^2 = x, y(0) = 1); tpsform(a, x)
 
and it gave an output that agreed with my work. I'm not sure what my syntax error is, any help would be much appreciated,
 
thanks! 

 

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