OFFSET
1,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..89
EXAMPLE
222 is in the sequence because 222 = 2*3*37, product of 3 distinct primes.
MAPLE
with(numtheory):
for n from 1 to 23 do:
for b from 1 to 9 do:
x:=(((10^n)- 1)/9)*b:y:=factorset(x):n1:=nops(y):
if bigomega(x)=3 and n1=3
then
printf(`%d, `, x):
else
fi:
od:
od:
MATHEMATICA
Select[Flatten@ Map[Map[Function[k, FromDigits@ Table[k, {#}]], Range[1, 9]] &, Range@ 20], Length@ # == 3 && Times @@ Last /@ # == 1 &@ FactorInteger@ # &] (* Michael De Vlieger, Feb 07 2016 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Feb 07 2016
STATUS
approved