script help with grep or regex ?

I have a shell script that gets a web page, after around half dozen
sed/awk one liners I end up with like[1]:

I would like to extract all the 7 digit numeric values, currently starting
with '313....', to use them further in the script

I'm hoping there is some better way ? (rather what I'm doing, 'grep 313')

[1]-------
Page: 1 Items: 1 - 2

Items(Total: 2 displaying 2)

3137973
stf, Stuff, morestuff, Stuff2:stuff3,
Date: 14/01/2014, Time: 09:30 AM
14/01/2014 09:30
Notes(0)

3137966
stf, Stuff, morestuff, Stuff2:stuff3,
Date: 06/02/2014, Time: 09:30 AM
06/02/2014 09:30
Notes(0)



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