Prime Curios! 23

Prime Curios! 23, Chris Caldwell's maintained mathematical curiosities reference, The Prime Pages, University of Tennessee at Martin, is consulted here for the number 23's classification as a Sophie Germain prime and its place in the chain with 47. Its strength is that it is a maintained mathematical reference, freely and immediately checkable. Its limit is that it is one page among many maintained by a single reference site maintainer across distinct number entries, of which this catalog separately holds another for the number 47; the year recorded here reflects the page as consulted on a continuously updated site rather than a single fixed edition.