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 A250132 #10 Jun 30 2017 11:32:27
%S A250132 4,24,72,288,1800,2160,17640,4032,9072,3360,18480,20160,240240,258720,
%T A250132 1386000,19219200,183783600,194594400,205405200,432432000,454053600,
%U A250132 8086478400,1207720800,1260230400,24942060000,25939742400,26937424800,195545750400,202529527200
%N A250132 Numerator of the harmonic mean of the first n composite numbers.
%H A250132 Colin Barker, <a href="/A250132/b250132.txt">Table of n, a(n) for n = 1..500</a>
%e A250132 a(3) = 72 because the first 3 composite numbers are [4,6,8] and 3 / (1/4+1/6+1/8) = 72/13.
%t A250132 Module[{comps=Select[Range[50],CompositeQ],len},len=Length[comps];Table[ HarmonicMean[ Take[comps,n]],{n,len}]]//Numerator (* _Harvey P. Dale_, Jun 30 2017 *)
%o A250132 (PARI)
%o A250132 harmonicmean(v) = #v / sum(k=1, #v, 1/v[k])
%o A250132 composite(n) = for(k=0, primepi(n), isprime(n++)&&k--); n \\ from A002808
%o A250132 s=vector(100); for(k=1, #s, s[k]=numerator(harmonicmean(vector(k, i, composite(i))))); s
%Y A250132 Cf. A250133 (denominators).
%K A250132 nonn
%O A250132 1,1
%A A250132 _Colin Barker_, Nov 14 2014