0,4

Ray Chandler, Table of n, a(n) for n = 0..310 (from Kamada link)

Makoto Kamada, Factorizations of 100...001.

a(n) = A104223(n-1), n>0. - R. J. Mathar, Aug 08 2008

a(n) = A001221(A062397(n)). - Ray Chandler, May 02 2017

a(11) = 4 because 10^11+1 = 11*11*23*4093*8779: 4 distinct factors.

Table[Length[FactorInteger[10^n + 1]], {n, 0, 50}] (* Stefan Steinerberger, Jun 13 2006 *)

PrimeNu[10^Range[0, 100]+1] (* The program will take some time to run *) (* Harvey P. Dale, Aug 27 2019 *)

Cf. A001221, A003021, A038371, A057934, A062397, A104223.

Sequence in context: A067438 A178250 A174550 * A104223 A057934 A058758

Adjacent sequences: A119701 A119702 A119703 * A119705 A119706 A119707

nonn

Lekraj Beedassy, Jun 09 2006

More terms from Don Reble, Jun 13 2006

approved