You can get the sequence of each probe in tabular or FASTA format from the Affymetrix support site: Human Genome U133 Plus 2.0 Array - Support Materials. I give a previous example for another Affymetrix array, here: Sequence corresponding to each probe id of affymetrix gene chip
You can also get the coding / mRNA sequence of the gene targeted by the probe in R via biomaRt. I give an example of this, here: A: getting gene sequence from probeset id
I believe there are other ways to do this, too.