I found solution
here
Dim IntList As List(Of Integer) = {5, 7, 8, 10, 15, 24, 26}.ToList
Dim ResultList = (From x In IntList Let nextindex = IntList.IndexOf(x) + 1 Let nextelement = IntList.ElementAt(If(nextindex = IntList.Count, nextindex - 1, nextindex)) Select nextelement - x).ToList()
result.RemoveAt(IntList.Count - 1)
ResultList = {2,1,2,5,9,2}