Fill a series in a non adjacent cells

[mostafaxx]

hello every one,
how can i fill a one step value series in a non adjacent cells?

for example i’ve cells

A20
A23
A24
A27
A30

i just want them incremented by 1
A20 val=2,
A23 val=3,
A24 val=4,
A27 val=5,
A30 val=6,
,
… val=7

[JohnSUN]

Insert a formula in cell A20

=MAX($A$1:A19)+1

Copy this cell

Insert in the all the necessary cells below

[tohuwawohu]

Simple but clever solution - +1 from me!