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 A068043 #9 Feb 06 2017 14:54:23
%S A068043 1,1,1,1,1,1,1,3,10,23,43,82,164,328,656,1312,2622,5243,10486,20972,
%T A068043 41945,83887,167773,335546,671092,1342184,2684360,5368712,10737422,
%U A068043 21474842,42949682,85899350,171798690,343597388,687194782,1374389558
%N A068043 Number of subsets of {1,2,3,...,n} that sum to 0 mod 25.
%F A068043 Empirical G.f.: -(x -1) * (4*x^29 +4*x^28 +4*x^27 -4*x^24 -4*x^23 -4*x^22 -3*x^21 -2*x^20 -x^19 -x^18 -x^17 -2*x^16 +4*x^15 +10*x^14 +4*x^13 -4*x^12 -6*x^11 -8*x^10 -9*x^9 -4*x^8 +2*x^7 +5*x^6 +6*x^5 +3*x^4 +2*x^3 +x^2 -1) / ((2*x -1)*(2*x^5 -1)*(2*x^25 -1)). [_Colin Barker_, Dec 23 2012]
%Y A068043 25th row of A068009.
%K A068043 nonn
%O A068043 0,8
%A A068043 _Antti Karttunen_, Feb 11 2002