checked through n=25
checked through n=75
checked through n=125
checked through n=175
checked through n=225
checked through n=275
checked through n=325
checked through n=375

primitive levels found: []
(levels divisible by 10,24,28,42 were skipped)
NOTE: absence of hits is computational evidence, not a nonexistence proof, because candidate generation uses floating-point screening.
elapsed=0:16.89
