OFFSET
1,1
COMMENTS
The sequence A063869 gives the least k such that sigma(k)=m^n for some m>1.
In this sequence, except n=2 -> m=3, the program gives m = 2 for n = 1 to 30.
All terms are squarefree. [Charles R Greathouse IV, Aug 19 2011]
FORMULA
a(n)=Min{x : A008472 (x)= m^n} for some m.
EXAMPLE
a(11) = 28546 because the sum of the distinct prime divisors {2, 7, 2039} is 2048 = 2^11.
MAPLE
with(numtheory):for n from 1 to 12 do:ii:=0:for k from 1 to 1000000 while(ii=0) do: ii:=0:x:=factorset(k):p1:=sum(x[i], i=1..nops(x)):jj:=0:for m from 2 to 10 while(jj=0) do :if p1=m^n then ii:=1:jj:=1: printf ( "%d %d \n", n, k):else fi:od:od:od:
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Aug 19 2011
STATUS
approved