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A113913 Number of distinct prime factors of 3^(3^n)+1. 1
1, 2, 4, 6, 11, 20, 27 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The term omega(3^(3^6)+1) was obtained with ECM factoring.

LINKS

Table of n, a(n) for n=0..6.

FORMULA

a(n) = A001221(A129290(n)).

MATHEMATICA

Table[PrimeNu[3^(3^n) + 1], {n, 1, 10}] (* G. C. Greubel, May 16 2017 *)

PROG

(PARI) for(x=1, 6, print1( omega(3^(3^x)+1), ", "))

CROSSREFS

Sequence in context: A000694 A164137 A018170 * A002097 A026757 A026385

Adjacent sequences:  A113910 A113911 A113912 * A113914 A113915 A113916

KEYWORD

hard,more,nonn

AUTHOR

Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Jan 29 2006

STATUS

approved

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Last modified October 20 07:17 EDT 2018. Contains 316378 sequences. (Running on oeis4.)