You can post the comment on https://www.codewars.com/topics/feature-requests
Thanks ;-)

Looks like the C# Translator used zero for a test case. It threw off a number of C# solutions! This'll display an ArgumentOutOfRangeException exception now, so that should be a good indicator :)

Issue is now fixed.

Formatting updated.

You can also do something like this:

var m = sequence.Skip(3).Aggregate(new { Item = sequence[2], Incr = seq[1] - seq[0] }, (acc, e) => {
    var candidate = e - acc.Item;
    if (candidate != acc.Incr)
        throw new ArgumentException("Non-linear sequence");
    return new { Item = e, Incr = candidate };
}.Incr;

I thought of this afterwards, but still just as effective. ;)

indeed, thx!