This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A017706 #12 Sep 08 2022 08:44:43
%S A017706 1,2097152,10460353203,4398046511104,476837158203125,609359740010496,
%T A017706 558545864083284007,9223372036854775808,109418989131512359209,
%U A017706 500000000000000000000,7400249944258160101211,11501279977342425366528
%N A017706 Denominator of sum of -21st powers of divisors of n.
%C A017706 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
%H A017706 G. C. Greubel, <a href="/A017706/b017706.txt">Table of n, a(n) for n = 1..10000</a>
%t A017706 Table[Denominator[DivisorSigma[21, n]/n^21], {n, 1, 20}] (* _G. C. Greubel_, Nov 05 2018 *)
%o A017706 (PARI) vector(20, n, denominator(sigma(n, 21)/n^21)) \\ _G. C. Greubel_, Nov 05 2018
%o A017706 (Magma) [Denominator(DivisorSigma(21,n)/n^21): n in [1..20]]; // _G. C. Greubel_, Nov 05 2018
%Y A017706 Cf. A017705.
%K A017706 nonn,frac
%O A017706 1,2
%A A017706 _N. J. A. Sloane_