every seventh = ?

In the line-up of "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23.......", 7,14 and 21 belong to the "every seventh"?

Context:

"Rather than 'rounding up the usual suspects', we now have a comprehensive molecular playlist of 1000 suspects," says Professor Jeffrey L Noebels, Professor of Neurology, Neuroscience and Human Genetics at Baylor College of Medicine. "Every seventh protein in this line-up is involved in a known clinical disorder, and over half of them are repeat offenders. Mining the postsynaptic proteome now gives researchers a strategic entry point, and the rest of us a front row seat to witness neuroscience unravel the complexity of human brain disorders."