OFFSET
1,1
COMMENTS
EXAMPLE
a(1) = 8 because 8 = 2^3 is the largest (only) 1-digit number that is divisible by exactly 3 primes (counted with multiplicity).
a(2) = 99 because 99 = 3^2 * 11 is the largest 2-digit number (of 21) that is divisible by exactly 3 primes (counted with multiplicity).
a(3) = 994 because 994 = 2 * 7 * 71 is the largest 3-digit number that is divisible by exactly 3 primes (counted with multiplicity).
MATHEMATICA
lndn3[n_]:=Module[{k=10^n-1}, While[PrimeOmega[k]!=3, k--]; k]; Array[ lndn3, 20] (* Harvey P. Dale, Jul 25 2019 *)
PROG
(PARI) A180927(n)=forstep(n=10^n-1, 10^(n-1), -1, bigomega(n)==3&return(n)) \\ M. F. Hasler, Jan 23 2011
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Jonathan Vos Post, Jan 23 2011
STATUS
approved