Pulling in a subset of a larger data set

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In Sheet1, I have a list of box numbers in Column A and a list of serial numbers in Column B:

1 100001
1 100002
1 100003
2 100004
2 100005
3 100006
3 100007
3 100008
etc...

In Sheet2 I want to input a list of box numbers in Column A:

1
2
3
etc...

I need an output of all the serial numbers from boxes listed in Sheet2 Column A into Sheet3 Column A. For example, inputting the following in Sheet2 Column A:

1
3

would produce the following in Sheet3 Column A

100001
100002
100003
100006
100007
100008


Thanks for your time!