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 A249950 #9 Aug 20 2017 12:17:34
%S A249950 1,16,648,6912,1080000,144000,57624000,526848000,144027072000,
%T A249950 160030080000,234300040128000,255600043776000,608349404190528000,
%U A249950 655145512205184000,701941620219840000,5989901825875968000,31267661899936670208000,3678548458816078848000
%N A249950 Numerator of the harmonic mean of the first n cubes.
%C A249950 A007408 contains the corresponding denominators.
%H A249950 Colin Barker, <a href="/A249950/b249950.txt">Table of n, a(n) for n = 1..750</a>
%e A249950 a(3) = 648 because the first 3 cubes are [1,8,27] and 3 / (1/1+1/8+1/27) = 648/251.
%t A249950 Table[Numerator[n/Sum[1/k^3,{k,1,n}]],{n,1,20}] (* _Vaclav Kotesovec_, Nov 14 2014 *)
%t A249950 Table[Numerator[HarmonicMean[Range[n]^3]],{n,20}] (* _Harvey P. Dale_, Aug 20 2017 *)
%o A249950 (PARI)
%o A249950 harmonicmean(v) = #v / sum(k=1, #v, 1/v[k])
%o A249950 s=vector(30); for(k=1, #s, s[k]=numerator(harmonicmean(vector(k, i, i^3)))); s
%Y A249950 Cf. A007408.
%K A249950 nonn
%O A249950 1,2
%A A249950 _Colin Barker_, Nov 13 2014