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 A282511 #29 Dec 15 2017 22:16:59
%S A282511 1,5,17,37,119,631,661,4807,995,2053,703,3599,3679,41309,42079,214091,
%T A282511 2829383,25864847,26250947,26611307,53898289,54553489,938220113,
%U A282511 135531719,136990319,2629070861,2654652461,2679594521,18923442047,19082164247,19237359287
%N A282511 Numerator of the sum of the reciprocals of the first n nonprimes.
%e A282511 The first few fractions are 1, 5/4, 17/12, 37/24, 119/72, 631/360, 661/360, 4807/2520, 995/504, 2053/
%e A282511 1008, 703/336, 3599/1680, ... - _N. J. A. Sloane_, Dec 15 2017
%t A282511 With[{nn = 45}, Numerator@ Accumulate[1/Complement[Range@ nn, Prime@ Range@ PrimePi@ nn]]] (* _Michael De Vlieger_, Feb 18 2017 *)
%o A282511 (PARI) a018252(n) = if(n==1, 1, my(i=1); forcomposite(c=1, , i++; if(i==n, return(c))))
%o A282511 a(n) = numerator(sum(k=1, n, 1/a018252(k))) \\ _Felix Fröhlich_, Feb 17 2017
%Y A282511 Cf. A018252 (nonprime numbers), A282512 (denominators).
%Y A282511 The following fractions are all related to each other: Sum 1/n: A001008/A002805, Sum 1/prime(n): A024451/A002110 and A106830/A034386, Sum 1/nonprime(n): A282511/A282512, Sum 1/composite(n): A250133/A296358.
%K A282511 nonn,frac
%O A282511 1,2
%A A282511 _Ralf Steiner_, Feb 17 2017
%E A282511 More terms from _Felix Fröhlich_, Feb 17 2017