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 A068041 #6 Sep 08 2022 13:33:03
%S A068041 1,1,1,1,1,1,2,6,14,26,52,103,205,410,820,1640,3278,6554,13108,26216,
%T A068041 52432,104860,209716,419432,838864,1677728,3355448,6710888,13421776,
%U A068041 26843552,53687104,107374192,214748368,429496736,858993472,1717986944
%N A068041 Number of subsets of {1,2,3,...,n} that sum to 0 mod 20.
%F A068041 Empirical G.f.: (x-1)^2*(4*x^12+4*x^11-x^10-7*x^9-11*x^8-15*x^7-15*x^6-11*x^5-5*x^4-2*x^3+x+1) / ((2*x-1)*(2*x^5-1)). [_Colin Barker_, Dec 22 2012]
%Y A068041 20th row of A068009.
%K A068041 nonn
%O A068041 0,7
%A A068041 _Antti Karttunen_, Feb 11 2002