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A017669 Numerator of sum of -3 th powers of divisors of n. 2
1, 9, 28, 73, 126, 7, 344, 585, 757, 567, 1332, 511, 2198, 387, 392, 4681, 4914, 757, 6860, 4599, 1376, 2997, 12168, 455, 15751, 9891, 20440, 3139, 24390, 147, 29792, 37449, 4144, 22113, 6192, 55261, 50654, 15435, 61544, 7371, 68922, 172, 79508, 24309, 10598 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Sum_{d|n} 1/d^k is equal to sigma_k(n)/n^k. So sequences A017665-A017712 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), A001157-A001160 (k=2,3,4,5), A013954-A013972 for k = 6,7,...,24. - Ahmed Fares (ahmedfares(AT)my-deja.com), Apr 05 2001.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

A017669[n_Integer] := Numerator[DivisorSigma[-3, n]]; A017669 /@ Range[100] (* Vladimir Joseph Stephan Orlovsky, Jul 21 2011 *)

CROSSREFS

Cf. A017670.

Sequence in context: A062451 A065959 A226333 * A001158 A171215 A053819

Adjacent sequences:  A017666 A017667 A017668 * A017670 A017671 A017672

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 16 14:51 EDT 2014. Contains 240600 sequences.