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URL: https://oeis.org/A082872

⇱ A082872 - OEIS

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A082872
a^n + b^n + c^n + ..., where a*b*c* ... is the prime factorization of n.
4
1, 4, 27, 32, 3125, 793, 823543, 768, 39366, 9766649, 285311670611, 539633, 302875106592253, 678223089233, 30531927032, 262144, 827240261886336764177, 775103122, 1978419655660313589123979, 95367433737777, 558545874543637210, 81402749386839765307625
OFFSET
1,2
COMMENTS
n*log_10(2) + log_10(log_2(n)) <= length(a(n)) <= n*log_10(n). - Martin Renner, Jan 18 2012
If m = p^k is a power of a prime then a(n) = Sum_{i=1..k} p^m = k*p^m is composite. - Martin Renner, Jan 31 2013
EXAMPLE
a(6) = a(2*3) = 2^6 + 3^6 = 793.
a(8) = a(2*2*2) = 2^8 + 2^8 + 2^8 = 768.
MAPLE
A082872 := proc(n)
local ps;
if n= 1 then
1;
else
ps := ifactors(n)[2] ;
add( op(2, p)*op(1, p)^n, p=ps) ;
end if;
end proc: # R. J. Mathar, Mar 12 2014
MATHEMATICA
Table[f = FactorInteger[n]; Total[Flatten[Table[Table[f[[i, 1]], {f[[i, 2]]}], {i, Length[f]}]]^n], {n, 25}] (* T. D. Noe, Feb 01 2013 *)
Table[Total[Flatten[Table[#[[1]], #[[2]]]&/@FactorInteger[n]]^n], {n, 30}] (* Harvey P. Dale, Jun 10 2016 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jason Earls, May 25 2003
STATUS
approved