

A017670


Denominator of sum of 3 th powers of divisors of n.


2



1, 8, 27, 64, 125, 6, 343, 512, 729, 500, 1331, 432, 2197, 343, 375, 4096, 4913, 648, 6859, 4000, 1323, 2662, 12167, 384, 15625, 8788, 19683, 2744, 24389, 125, 29791, 32768, 3993, 19652, 6125, 46656, 50653, 13718, 59319, 6400, 68921, 147, 79507, 21296, 10125
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OFFSET

1,2


COMMENTS

Sum_{dn} 1/d^k is equal to sigma_k(n)/n^k. So sequences A017665A017712 also give the numerators and denominators of sigma_k(n)/n^k for k = 1..24. The power sums sigma_k(n) are in sequences A000203 (k=1), A001157A001160 (k=2,3,4,5), A013954A013972 for k = 6,7,...,24.  comment from Ahmed Fares (ahmedfares(AT)mydeja.com), Apr 05 2001.


LINKS

Table of n, a(n) for n=1..45.


FORMULA

Denominator of Sum_{dn} 1/d^3.


MATHEMATICA

A017670[n_Integer] := Denominator[DivisorSigma[3, n]]; A017670 /@ Range[100] (* Vladimir Joseph Stephan Orlovsky, Jul 21 2011 *)


CROSSREFS

Cf. A017669.
Sequence in context: A211641 A062686 A093322 * A126200 A213491 A076989
Adjacent sequences: A017667 A017668 A017669 * A017671 A017672 A017673


KEYWORD

nonn,frac


AUTHOR

N. J. A. Sloane.


STATUS

approved



