Hello,
Lets' assume a the side and r the commun added number
sides: a,a+r,a+2r
p=a+a+r+a+2r=3a+3r
==>a+r=10
Side 0 doesn't exist
a=1,r=9==>1,10,19
a=2,r=8==>2,10,18
a=3,r=7==>3,10,17
a=4,r=6==>4,10,16
a=5,r=5==>5,10,15
a=6,r=4==>6,10,14
a=7,r=3==>7,10,13
a=8,r=2==>8,10,12
a=9,r=1==>9,10,11