[seqfan] semiprimes in step-6 arithmetic progression A125025

[Richard J. Mathar]

In the list of achievable lengths of arithmetic progressions of
semiprimes, A125025, there still is a lower bound a(6), semiprime sequences 
with gaps/step-size 6, that is conjectured.  [The bound is actually found by a 
brute-force-attack checking semiprimes up to 11 million....]

It may be useful to either confirm a(6), i.e., to proof that there is no sequence 
of 16 or more semiprimes with gap=6, or to truncate the sequence to a(1..5) and 
to add a(6)>=15, a(12)>=14, a(18)>=15, a(24)>=13..  as comments
(the latter read from my PDF file in A124750).

RJM