perl -i.bak -F, -ane '
    if ($F[0]+1 == $F[1] and $F[1]+1 == $F[2]) {warn "row $.: $_"} else {print}
' file.csv 2>file.log 
##</code><code>##

for line in file: 
    for i in range(1,4):
        if ($F[0]+ i == $F[1] and $F[1]+i == $F[2]): 
           remove line