XSLT-displaying the number followed by alphabets

<PassengerList>
<SeatNumber>1A</SeatNumber>
<SeatNumber>1B</SeatNumber>
<SeatNumber>1D</SeatNumber>
<SeatNumber>1E</SeatNumber>
<SeatNumber>1F</SeatNumber>
<SeatNumber>1G</SeatNumber>
<SeatNumber>2B</SeatNumber>
<SeatNumber>2D</SeatNumber>
<SeatNumber>3A</SeatNumber>
<SeatNumber>3B</SeatNumber>
<SeatNumber>3D</SeatNumber>
<SeatNumber>3E</SeatNumber>
<SeatNumber>4A</SeatNumber>
<SeatNumber>4B</SeatNumber>
<SeatNumber>4E</SeatNumber>
<SeatNumber>4F</SeatNumber>
<SeatNumber>4G</SeatNumber>
<SeatNumber>4J</SeatNumber>
</PassengerList>

I need the output to be:

1ABDEFG2BD3ABDE4ABEFGJ

Note: Outputtype = "text"
I am strugglling for the last 2 days for this required output. Can you please help me in displaying like above with numbers followed by alphabets.