Question 954718
<pre>
3128, 3130, 3130, 3131,

That seems to be starting with the sequence of integers: 

3128, 3129, 3130, 3131, 3132, 3133, 3134, 3135, 3136,...

Grouping them into threes:

(3128, 3129, 3130), (3131, 3132, 3133), (3134, 3135, 3136)...

and adding 1 to the middle number of each group

(3128, 3129, 3130), (3131, 3132, 3133), (3134, 3135, 3136),...
         +1                  +1                  +1
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(3128, 3130, 3130), (3131, 3133, 3133), (3134, 3136, 3136),...


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3, 1, 2, 3, 2, 4, 5, 6, ?, ?,

Put in some parentheses and question marks:

3, (1, 2, 3), 2, (4, 5, 6), ?, (?, ?, ?), ?, (?, ?, ?), ...    

Extend the pattern (in red):

3, (1, 2, 3), 2, (4, 5, 6),<font color="red"><b> 1, (7, 8, 9), 0, (10, 11, 12), ...</font></b>

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F, P, N, ?, M,

I have no idea.  Sorry!

Edwin</pre>