[seqfan] Smallest number that contains the first n semiprimes as substrings

[Jonathan Post]

4, 46, 469, 10469,  101469, 10141569, 101421569

Smallest number that contains the first n semiprimes as substrings.
Semiprime analogue of A054261.

Is this "base" seq right so far?  How does it get extended?  Is a
modification of
http://www.math.niu.edu/~rusin/known-math/95/1000digits
the way to proceed?

Cf. A000040, A001358, A054260, A035239, A178057, A144565, A169798