A180341 a(n) = k is the smallest number such that n is the number of distinct primes dividing k^k + 1.

0, 3, 5, 9, 13, 11, 18, 23, 40, 30, 27, 60, 35, 45, 91, 69, 98, 63, 119

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 * A348746 A177078 A187906

Adjacent sequences: A180338 A180339 A180340 * A180342 A180343 A180344

Keyword

nonn,hard

Author

Michel Lagneau, Jan 18 2011

Status

approved