[R] Data transformation

[jenny tan]

Hi there,

Wonder if someone who is R-savvy can help me with the following task (see 
below) that I occasionally do work and gets quite tedious if I do it 
manually. Thanks in advance!

jenny.

-----------------

I have a column of data that looks like this:
NA18501
NA18502
NA18504
NA18505
NA18507
NA18508
NA18516
NA18517
NA18522
NA18523

And I want to duplicate the values and sort of "interweave" them to look 
like this:

NA18501
NA18501
NA18502
NA18502
NA18504
NA18504
NA18505
NA18505
NA18507
NA18507
NA18508
NA18508
NA18516
NA18516
NA18517
NA18517
NA18522
NA18522
NA18523
NA18523