OFFSET
0,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..204
Makoto Kamada, Factorizations of 11...119.
Markus Tervooren, Factorizations of (1)w9
FORMULA
EXAMPLE
The number of distinct prime divisors of 19 is 1 (prime).
The number of distinct prime divisors of 119 is 2: 119 = 7 * 17.
The number of distinct prime divisors of 1119 is 2: 1119 = 3 * 373.
MAPLE
seq(nops(numtheory:-factorset((10^n + 71)/9)), n=1..70); # Robert Israel, Apr 19 2015
MATHEMATICA
Table[PrimeNu[(10^n + 71)/9], {n, 50}] (* Alonso del Arte, Apr 18 2015 *)
PROG
(Magma) [(#(PrimeDivisors((10^n+71)div 9))): n in [1..60]]; // Vincenzo Librandi, Apr 19 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Apr 18 2005
STATUS
approved