merge(concantenate) cells by order

In column A there are items like a,b,c,d,e,f,g,..... and goes on.
I want to merge(concantenate) items in column B like ab, ac,ad,ae,af,ag,bc,bd,be,bf,bg.......... and goes on.
I need by formula if possible, or macro .

Attached table sample data explained how to be listed.

Thanks in advance for any reply and help.
Regards,
turist

What about (for "a"):

Formula:

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Then apply that to the cells you need to display "a & (whatever letter)"

Then for "b & c" simply change it to:

Formula:

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Then apply this for the cells you want

Originally Posted by alexander.small

What about (for "a"):

Formula:

Please Login or Register  to view this content.

Then apply that to the cells you need to display "a & (whatever letter)"

Then for "b & c" simply change it to:

Formula:

Please Login or Register  to view this content.

Then apply this for the cells you want

Thanks for reply,
But it is easiest way of course manually.
If items go down thousands rows , how can be managed manually , it is a disaster.
So I need a formula only can be copied to down without any change.
Sorry, your solution will not working for a huge file.