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 A138316 #11 Aug 28 2018 15:01:12
%S A138316 1,2,5,5,11,13,41,41,41,11,113,113,77,241,497,497,1009,1009,3067,3067,
%T A138316 3127,3199,35549,35549,35549,36209,36209,36209,255443,262373,264221,
%U A138316 264221,266993,135229,17048,17048,22859,69347,139849,139849,70271,35713
%N A138316 Numerators of the squarefree totient analogs of the harmonic numbers F_n.
%C A138316 F_n-H_n approaches a constant, 'kappa', conjectured to be equivalent to the difference of B_3-gamma, where B_3 is Mertens' 3rd constant and gamma is Euler's constant.
%H A138316 G. C. Greubel, <a href="/A138316/b138316.txt">Table of n, a(n) for n = 1..10000</a>
%H A138316 Dick Boland, <a href="http://www.imathination.org/kappa/kappa.pdf">An Analog of the Harmonic Numbers Over the Squarefree Integers</a>
%F A138316 a(n) = numerator[sum(k=1 to n)mu^2(k)/phi(k)] where mu(k) is the Mobius function and phi(k) is Euler's Totient function.
%e A138316 Numerators of F_n, e.g., F_1 = (1/1), F_2 = (1/1 + 1/1), ... F_11 = (1/1 + 1/1 + 1/2 + 0 + 1/4 + 1/2 + 1/6 + 0 + 0 + 1/4 + 1/10).
%t A138316 Table[Numerator[Sum[MoebiusMu[k]^2/EulerPhi[k], {k, 1, n}]], {n, 1, 60}]
%o A138316 (PARI) a(n) = numerator(sum(k=1, n, if (issquarefree(k), 1/eulerphi(k)))); \\ _Michel Marcus_, Aug 28 2018
%Y A138316 Cf. A138312, A138313, A138312, A138317, A138320, A138321, A083343, A001620.
%K A138316 frac,nonn
%O A138316 1,2
%A A138316 Dick Boland (abstract(AT)imathination.org), Mar 13 2008, Mar 27 2008