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A119704 a(n) = number of distinct prime factors of 10^n+1, omega(10^n+1). 3
1, 1, 1, 3, 2, 2, 2, 2, 2, 5, 3, 4, 3, 3, 4, 7, 5, 4, 3, 2, 4, 7, 4, 5, 3, 5, 3, 7, 4, 3, 7, 2, 4, 8, 4, 5, 6, 4, 3, 9, 4, 3, 7, 4, 4, 12, 4, 4, 9, 4, 7, 8, 4, 2, 6, 9, 5, 6, 5, 4, 6, 3, 3, 11, 3, 6, 8, 2, 4, 10, 11, 3, 5, 4, 7, 11, 6, 11, 7, 4, 9, 11, 3, 7, 8, 8, 3, 8, 4, 4, 11, 6, 4, 8, 4, 6, 8, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

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

Makoto Kamada, Factorizations of 100...001.

FORMULA

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

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

EXAMPLE

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

MATHEMATICA

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

CROSSREFS

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

Sequence in context: A067438 A178250 A174550 * A104223 A057934 A058758

Adjacent sequences:  A119701 A119702 A119703 * A119705 A119706 A119707

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Jun 09 2006

EXTENSIONS

More terms from Don Reble, Jun 13 2006

STATUS

approved

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Last modified December 11 10:48 EST 2018. Contains 318049 sequences. (Running on oeis4.)