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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 14 12:04 EST 2019. Contains 329979 sequences. (Running on oeis4.)