I am a computer scientist revisiting integration after a long time. I am stuck with this simple-looking integral that's turning out to be quite painful (to me). I was wondering if one of you could help.

The goal is to solve the integral

$\displaystyle \int_{0}^{\infty} e^{-(x - t)^2/2 \sigma^2} x^n\ dx $

Note that this is the convolution of the Gaussian centered around 0 with the function that equals $x^n$ for $x > 0$, and 0 elsewhere (modulo scaling).

In particular, I would be interested in seeing any relationship with the integral

$\displaystyle \int_{-\infty}^{\infty} e^{-(x - t)^2/2 \sigma^2} x^n\ dx $

which I have worked out.

Any suggestions?

Thanks in advance,