Many of these seem to be even semiprimes.
Is this sequence infinite, and if so, can someone exhibit an explicitely calculable subsequence?
Table of n, a(n) for n=1..38.
Sequence in context: A341080 A279519 A307188 * A212816 A183980 A101754
Adjacent sequences: A209318 A209319 A209320 * A209322 A209323 A209324
M. F. Hasler, Jan 19 2013