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A001158
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sigma_3(n): sum of cubes of divisors of n.
(Formerly M4605 N1964)
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69
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1, 9, 28, 73, 126, 252, 344, 585, 757, 1134, 1332, 2044, 2198, 3096, 3528, 4681, 4914, 6813, 6860, 9198, 9632, 11988, 12168, 16380, 15751, 19782, 20440, 25112, 24390, 31752, 29792, 37449, 37296, 44226, 43344, 55261, 50654, 61740, 61544
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OFFSET
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1,2
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COMMENTS
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If the canonical factorization of n into prime powers is the product of p^e(p) then sigma_k(n) = Product_p ((p^((e(p)+1)*k))-1)/(p^k-1).
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. - comment from Ahmed Fares (ahmedfares(AT)my-deja.com), Apr 05 2001.
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math.Series 55, Tenth Printing, 1972, p. 827.
T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1976, page 38.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..10000
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math.Series 55, Tenth Printing, 1972, p. 827.
Y. Puri and T. Ward, Arithmetic and growth of periodic orbits, J. Integer Seqs., Vol. 4 (2001), #01.2.1.
Eric Weisstein's World of Mathematics, Divisor Function.
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FORMULA
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Multiplicative with a(p^e) = (p^(3e+3)-1)/(p^3-1). - David W. Wilson, Aug 01, 2001.
Dirichlet g.f. zeta(s)*zeta(s-3) [R. J. Mathar, Mar 04 2011].
G.f.: sum(k>=1, k^3*x^k/(1-x^k)). - Benoit Cloitre, Apr 21 2003
Equals A051731 * [1, 8, 27, 64, 125,...] = A127093 * [1, 4, 9, 16, 25,...]. - Gary W. Adamson, Nov 02 2007
L.g.f.: -log(prod(j>=1, (1-x^j)^(j^2))) = 1/1*z^1 + 9/2*z^2 + 28/3*z^3 + 73/4*z^4 + ... + a(n)/n*z^n + ... - Joerg Arndt, Feb 04 2011
a(n)=Sum{d|n} tau_{-2}^(d)*J_3(n/d), where tau_{-2} is A007427 and J_3 A059376. - Enrique Pérez Herrero, Jan 19 2013
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MATHEMATICA
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Table[DivisorSigma[3, n], {n, 100}]
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PROG
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(PARI) N=99; q='q+O('q^N);
Vec(sum(n=1, N, n^3*q^n/(1-q^n))) /* show terms */ /* Joerg Arndt, Feb 04 2011 */
(Sage) [sigma(n, 3) for n in xrange(1, 40)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 04 2009]
(Maxima) makelist(divsum(n, 3), n, 1, 100); /* Emanuele Munarini, Mar 26 2011 */
(MAGMA) [DivisorSigma(3, n): n in [1..40]]; // Bruno Berselli, Apr 10 2013
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CROSSREFS
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Cf. A000005, A000203, A001157.
Cf. A051731, A127093.
Sequence in context: A062451 A065959 A017669 * A171215 A053819 A085292
Adjacent sequences: A001155 A001156 A001157 * A001159 A001160 A001161
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KEYWORD
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nonn,easy,nice,mult
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AUTHOR
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N. J. A. Sloane, R. K. Guy
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EXTENSIONS
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Corrected Mathematica code T. D. Noe, Mar 22 2009
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STATUS
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approved
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