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
G. C. Greubel, Table of n, a(n) for n = 1..10000
FORMULA
From Amiram Eldar, Apr 02 2024: (Start)
sup_{n>=1} a(n)/A017706(n) = zeta(21).
Dirichlet g.f. of a(n)/A017706(n): zeta(s)*zeta(s+21).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k)/A017706(k) = zeta(22). (End)
MATHEMATICA
Table[Numerator[DivisorSigma[21, n]/n^21], {n, 1, 20}] (* G. C. Greubel, Nov 05 2018 *)
PROG
(PARI) vector(20, n, numerator(sigma(n, 21)/n^21)) \\ G. C. Greubel, Nov 05 2018
(Magma) [Numerator(DivisorSigma(21, n)/n^21): n in [1..20]]; // G. C. Greubel, Nov 05 2018
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
STATUS
approved