OFFSET
0,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..229
FORMULA
EXAMPLE
If n=1, then the number of distinct prime divisors of 91 is 2.
If n=2, then the number of distinct prime divisors of 991 is 1 (a prime).
If n=3, then the number of distinct prime divisors of 9991 is 2.
MAPLE
A105259 := proc(n) local x ; x := [1, seq(9, k=1..n)] ; add(op(i, x)*10^(i-1), i=1..nops(x)) ; numtheory[factorset](%) ; nops(%) ; end proc: # R. J. Mathar, Aug 24 2011
MATHEMATICA
Table[PrimeNu[10^(n + 1) - 9], {n, 0, 50}] (* G. C. Greubel, May 10 2017 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Apr 14 2005
EXTENSIONS
More terms from Amiram Eldar, Jan 24 2020
STATUS
approved