Counting Number If Not Sequence

[muhammad susanto]

hi all..
i have a list.. but into list contains "jumping" number / not series..
how to determine , count of number not series / not sequence

date Query function with date filter.xlsx
	G
2	sequences list
3	1
4	2
5	3
6	5
7	8
8	9
9	10
10	11
11	13
12	14
13	17
Sheet1

the answer is 6, how to determine it?
6 from (4,6,7,12.15.16 as jumping number)
please, don't use helper column
thank in advance

susanto

 

[muhammad susanto]

View attachment 53078
if number update not in last cell (number 20), the result is wrong
my data ascending and not duplicate

ups...sorry you right man.

 

[muhammad susanto]

Sorry, I don't understand. Why is 9 wrong?

The sequence is missing 9 numbers (8,10,12,13,14,15,17,18, and 19)

ups..you're right man..