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 A265391 #16 Sep 08 2022 08:46:14
%S A265391 1,3,3,11,3,9,3,25,11,9,3,11,3,9,9,137,3,11,3,11,9,9,3,25,11,9,25,11,
%T A265391 3,27,3,49,9,9,9,121,3,9,9,25,3,27,3,11,11,9,3,137,11,11,9,11,3,25,9,
%U A265391 25,9,9,3,33,3,9,11,363,9,27,3,11,9,27,3,275,3,9,11
%N A265391 a(n) = numerator of Sum_{d|n} 1 / tau(d).
%C A265391 a(n) = numerator of Sum_{d|n} 1 / A000005(d).
%H A265391 G. C. Greubel, <a href="/A265391/b265391.txt">Table of n, a(n) for n = 1..5000</a>
%F A265391 a(n) = [Sum_{d|n} 1 / tau(d)] * A265392(n) = A265390(n) * A265392(n) / A253139(n).
%F A265391 a(1) = 1; a(p) = 3 for p = prime.
%e A265391 For n = 6; divisors d of 6: {1, 2, 3, 6}; tau(d): {1, 2, 2, 4}; Sum_{d|6} 1 / tau(d) = 1/1 + 1/2 + 1/2 + 1/4 = 9 / 4; a(n) = 9 (numerator).
%t A265391 Table[Numerator[Sum[1/DivisorSigma[0, d], {d, Divisors@ n}]], {n, 75}] (* _Michael De Vlieger_, Dec 09 2015 *)
%o A265391 (Magma) [Numerator(&+[1/NumberOfDivisors(d): d in Divisors(n)]): n in [1..100]]
%o A265391 (PARI) a(n) = numerator(sumdiv(n, d, 1/numdiv(d))); \\ _Michel Marcus_, Dec 09 2015
%Y A265391 Cf. A000005, A253139, A265390, A265392 (denominator), A265393.
%K A265391 nonn,frac
%O A265391 1,2
%A A265391 _Jaroslav Krizek_, Dec 08 2015