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 A068040 #6 Aug 27 2018 14:55:10
%S A068040 1,1,1,1,1,1,2,7,14,27,54,108,216,431,862,1724,3450,6899,13798,27596,
%T A068040 55190,110378,220754,441506,883010,1766020,3532046,7064092,14128182,
%U A068040 28256364,56512728,113025456,226050910,452101820,904203640,1808407284
%N A068040 Number of subsets of {1,2,3,...,n} that sum to 0 mod 19.
%F A068040 Empirical G.f.: -(2*x^19+x^17-2*x^16+x^13+x^9-3*x^7+x^5+x^4+x^3+x^2+x-1) / ((2*x-1)*(2*x^19-1)). - _Colin Barker_, Dec 22 2012
%Y A068040 19th row of A068009.
%K A068040 nonn
%O A068040 0,7
%A A068040 _Antti Karttunen_, Feb 11 2002