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A180341 a(n) = k is the smallest number such that n is the number of distinct primes dividing k^k + 1. 0
0, 3, 5, 9, 13, 11, 18, 23, 40, 30, 27, 60, 35, 45, 91, 69, 98, 63, 119 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

EXAMPLE

a(6) = 11 because the 6 distinct primes dividing 11^11 + 1 = 285311670612 are

  {2, 3, 23, 89, 199, 58367}.

MAPLE

with(numtheory):for n from 1 to 8 do:ind:=0:for k from 1 to 40 while(ind=0)

  do: x:=k^k+1:y:=nops(factorset(x)):if y=n then ind:=1:printf(`%d, `, k):else

  fi:od: od:

CROSSREFS

Cf. A014566.

Sequence in context: A275843 A161866 A102968 * A177078 A187906 A187229

Adjacent sequences:  A180338 A180339 A180340 * A180342 A180343 A180344

KEYWORD

nonn,hard

AUTHOR

Michel Lagneau, Jan 18 2011

STATUS

approved

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Last modified April 23 03:26 EDT 2019. Contains 322380 sequences. (Running on oeis4.)