

A115973


Number of distinct prime factors of p^p + 1 where p is prime(n).


1



1, 2, 3, 3, 6, 5, 3, 5, 8, 7, 7, 7, 6, 8, 10, 8, 9, 8, 7, 8, 4, 7, 12, 6, 8, 7, 12, 9, 6, 9, 7, 17, 9, 9
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OFFSET

1,2


COMMENTS

a(35) >= 9. See link to factordb.com  Hugo Pfoertner, Aug 07 2019


LINKS

Table of n, a(n) for n=1..34.
Chris Caldwell, The First 1000 Primes.
Dario Alejandro Alpern, Factorization using the Elliptic Curve Method
factordb.com, Status of prime(n)^prime(n)+1.


EXAMPLE

If p=29 then (29^29 + 1) contains 7 distinct prime factors.


MATHEMATICA

f[n_] := Length@ FactorInteger[Prime[n]^Prime[n] + 1]; Array[f, 20]  Robert G. Wilson v, Apr 06 2006


PROG

(PARI) { for(n=1, 20, p = prime(n); d = factor(p^p+1); dec=matsize(d); print1(dec[1], ", "); ); }  R. J. Mathar, Mar 29 2006


CROSSREFS

Cf. A125137.
Sequence in context: A266286 A045892 A160791 * A057047 A101447 A119322
Adjacent sequences: A115970 A115971 A115972 * A115974 A115975 A115976


KEYWORD

nonn,more,hard


AUTHOR

Parthasarathy Nambi, Mar 14 2006


EXTENSIONS

8 more terms from R. J. Mathar, Mar 29 2006
a(19)a(25) from Robert G. Wilson v, Apr 06 2006
a(26)a(32) from Sean A. Irvine, Oct 20 2011
a(33), a(34) from Hugo Pfoertner, Aug 07 2019


STATUS

approved



