Problem 2800. arithmetic progression

I've written a program to generate the first few terms of arithmetic progressions. I've noticed something odd though, there's always one wrong term. Surely, there couldn't be a bug in my code, could it?

Can you tell me the position of the wrong term, and return the correct sequence?

For example, given

errorsequence = [2 4 7 8 10]; %arithmetic sequence starting at 2 with increment 2

then

errorposition = 3;
truesequence = [2 4 6 8 10];