OFFSET
2,3
COMMENTS
If a(48) != -1, then a(48) > 120. - Chai Wah Wu, Jul 29 2017
MATHEMATICA
Table[-1 + Length@ NestWhileList[FromDigits[#, 3] &@ Flatten@ Map[IntegerDigits[#, 3] &, FactorInteger[#] /. {p_, e_} /; p > 0 :> If[e == 1, p, {p, e}]] &, n, ! PrimeQ@ # &], {n, 2, 47}] (* Michael De Vlieger, Jul 29 2017 *)
CROSSREFS
KEYWORD
nonn,more,base
AUTHOR
Chai Wah Wu, Jul 27 2017
STATUS
approved