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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 (list; graph; refs; listen; history; text; internal format)
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(p^m,i=1..k) = k*p^m is composite. - Martin Renner, Jan 31 2013

LINKS

T. D. Noe, Table of n, a(n) for n = 1..100

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

Cf. A082813, A082814, A051674.

Sequence in context: A068349 A129204 A239283 * A274854 A054411 A051506

Adjacent sequences:  A082869 A082870 A082871 * A082873 A082874 A082875

KEYWORD

nonn,easy

AUTHOR

Jason Earls, May 25 2003

STATUS

approved

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Last modified July 5 04:30 EDT 2020. Contains 335459 sequences. (Running on oeis4.)